JP2009262163A - Method and apparatus for alignment adjustment, and laser beam machining apparatus equipped with the same - Google Patents

Abstract

A laser processing apparatus capable of surely adjusting the alignment of a laser without complicating the configuration of a laser processing head.
The present invention relates to a laser processing apparatus (1) for processing a workpiece with a laser guided by a liquid jet, a jet nozzle (18) for injecting a liquid to form a liquid column, and a liquid The laser optical system (4) that focuses the laser in the column, and the jet nozzle and laser focus move relative to each other so that the laser focus can be aligned with a predetermined target focus position relative to the jet nozzle entrance opening. The relative movement mechanism (12) to be operated, the liquid column ejected from the jet nozzle and the light-transmitting plate (20) that receives the laser, and the laser that has been disposed and projected so that the laser transmitted through the light-transmitting plate is projected And a light receiving member (24) for aligning the focal point of the laser based on the above image.
[Selection] Figure 1

Description

  The present invention relates to an alignment adjustment method and apparatus, and a laser processing apparatus including the alignment adjustment method, and more particularly, to an alignment adjustment method and apparatus for aligning a laser focus of a laser processing apparatus, and a laser processing apparatus including the alignment adjustment method and apparatus.

  Japanese Patent Laying-Open No. 2005-288472 (Patent Document 1) describes a method of aligning a hybrid machining apparatus and a hybrid machining apparatus. In this axial alignment method, the laser and water jet flow are axially aligned by measuring the intensity of Raman scattered light generated when the laser is guided through the water jet flow.

  Japanese Patent No. 2732230 (Patent Document 2) describes a coaxial observation apparatus in laser beam processing. In this coaxial observation device, in order to observe the irradiation position of the machining laser on the object to be machined, the observation laser is incident from the middle of the optical system that guides the machining laser using a half mirror or the like. Yes. Further, in this apparatus, the observation laser reflected by the processing object is guided to the CCD camera through a part of the optical system of the processing laser, and the processing object is observed.

JP 2005-288472 A Japanese Patent No. 2732230

  However, in the alignment described in Japanese Patent Application Laid-Open No. 2005-288472, Raman scattered light generated when light passes through the transparent medium is observed, so a special device for observing the Raman scattered light is necessary. There is a problem of becoming. In addition, this method has a problem that it is easily affected by disturbance because the alignment state is indirectly observed by Raman scattered light.

  In the coaxial observation device described in Japanese Patent No. 2732230, light used for alignment is incident on the middle of the optical system for guiding the processing laser, and light necessary for observation is branched from the middle of the optical system. Therefore, there is a problem that the configuration of the optical system becomes complicated. Furthermore, this apparatus has a problem that the transmission efficiency of the processing laser is lowered because it is necessary to provide a structure for combining or branching light in the middle of the optical system. In particular, in a laser processing apparatus of the type that guides the laser for processing by the ejected liquid column, the structure of the irradiation head becomes very complicated if the optical system becomes complicated, so the weight of the irradiation head increases and maintenance becomes difficult. Problems such as an increase in driving force necessary for driving the irradiation head become significant.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an alignment adjustment method and apparatus capable of reliably performing laser alignment adjustment without complicating the configuration of the laser processing head, and a laser processing apparatus including the alignment adjustment method and apparatus. Yes.

  In order to solve the above-described problems, the present invention is a laser processing apparatus that processes a workpiece by a laser guided by a liquid jet, and includes a jet nozzle that ejects liquid to form a liquid column, and a liquid column A laser optical system that focuses the laser inside, and a relative movement mechanism that moves the jet nozzle and laser focus relative to each other so that the laser focus can be aligned with a predetermined target focus position relative to the inlet opening of the jet nozzle A liquid column ejected from the jet nozzle and a light-transmitting plate that receives the laser; and a laser that has passed through the light-transmitting plate is projected, and the laser is focused on the basis of the projected laser image. And a light receiving member for positioning.

  In the present invention configured as described above, liquid is ejected from the jet nozzle to form a liquid column. The laser optical system focuses the laser in the liquid column, and the laser is guided by the liquid jet. The laser guided by the liquid jet is received by the translucent plate, and the laser passes through the translucent plate. The laser that has passed through the light transmitting plate is projected onto the light receiving member, and an image of the laser is formed on the light receiving member. Based on the laser image on the light receiving member, a relative movement mechanism for moving the jet nozzle and the focal point of the laser relative to each other is operated to align the focal point of the laser to a predetermined target focal position.

  According to the present invention configured as described above, since the focal point of the laser is aligned with the target focal position based on the image of the laser on the light receiving member, it is possible to reliably perform the laser without complicating the configuration of the head. Alignment adjustment can be performed.

In this invention, Preferably, it has an imaging means which images the image of the laser projected on the light-receiving member further.
According to the present invention configured as described above, the image of the laser projected onto the light receiving member is picked up by the image pickup means, so that alignment can be performed based on the picked up image.

  In the present invention, it is preferable to further include an alignment control means for controlling the relative movement mechanism based on the image picked up by the image pickup means and moving the focal point of the laser to the target focus position.

  According to the present invention configured as described above, the alignment control means controls the relative movement mechanism to move the focus of the laser to the target focus position, so that alignment can be performed automatically.

  In the present invention, preferably, the alignment control means (a) moves the focal point of the laser in a plane orthogonal to the axis of the jet nozzle and moves the focal point of the laser on the axis of the jet nozzle; and (b) Moving the focal point of the laser in the axial direction of the jet nozzle and moving the focal point of the laser onto the inlet opening surface of the jet nozzle.

  In the present invention configured as described above, the alignment control means aligns the focal point of the laser with the axis of the jet nozzle and then aligns with the inlet opening surface of the jet nozzle.

In the present invention, preferably, step (a) comprises (a1) focusing the laser so that the spot diameter of the laser formed on the inlet opening surface of the jet nozzle is larger than the diameter of the jet nozzle. A step of moving in the axial direction; and (a2) a step of moving the focal point of the laser in a plane perpendicular to the axis of the jet nozzle so that the image of the laser is minimized.
According to the present invention configured as described above, the focal point of the laser can surely coincide with the axis of the jet nozzle.

In the present invention, preferably, the jet nozzle is made of a material that transmits the laser, and step (a) includes (a1) moving the focal point of the laser to a first offset position off the inlet opening of the jet nozzle, Forming a first image in which the direction of the liquid column is missing on the light receiving member; and (a2) moving the laser focus to a second offset position different from the first offset position, which is out of the jet nozzle inlet opening. And forming a second image in which the direction of the liquid column is missing on the light receiving member; and (a3) a first straight line that passes through the first offset position and is oriented in the direction of the lack of the first image; , Obtaining an intersection point with a second straight line passing through the second offset position and directed in the direction of the defect of the second image, and moving the focal point of the laser to the position of the intersection point.
According to the present invention configured as described above, it is possible to make the focal point of the laser coincide with the axis of the jet nozzle only by obtaining at least two laser images.

  In the present invention, preferably, step (b) includes (b1) moving the focal point of the laser within a plane perpendicular to the axis of the jet nozzle in a predetermined offset direction, and (b2) laser. Moving the laser focus in the axial direction of the jet nozzle so that the image of the laser beam becomes the darkest, and (b3) offsetting the laser focus in the direction orthogonal to the offset direction in a plane perpendicular to the axis of the jet nozzle Moving the distance.

  According to the present invention configured as described above, it is possible to make the focal point of the laser coincide with the inlet opening surface of the jet nozzle only by obtaining the position where the image of the laser is darkest.

In the present invention, the offset distance is preferably approximately equal to the radius of the nozzle hole of the jet nozzle.
According to the present invention configured as described above, the focal point of the laser can be reliably matched with the inlet opening surface of the jet nozzle.

  In the present invention, preferably, step (b) includes (b1) a step of determining the range in which the laser image is larger than a predetermined diameter by moving the laser focus in the axial direction of the jet nozzle, and (b2) determination. Moving the focal point of the laser to an intermediate point in the defined range.

  According to the present invention configured as described above, the focal point of the laser can be made to coincide with the inlet opening surface of the jet nozzle only by moving the focal point of the laser in the axial direction of the jet nozzle.

  The present invention also relates to an alignment adjustment method for aligning the focal point of the laser of the laser processing apparatus of the present invention, wherein (a) the spot diameter of the laser formed on the inlet opening surface of the jet nozzle is the diameter of the jet nozzle. (B) moving the laser focus in a plane perpendicular to the jet nozzle axis so that the laser image is minimized. (C) moving the focal point of the laser within a plane perpendicular to the axis of the jet nozzle within a predetermined offset distance in a predetermined offset direction, and (d) so that the laser image is darkest. Moving the laser focus in the axial direction of the jet nozzle; and (e) moving the laser focus to the jet nozzle. In a plane perpendicular to the axis, it is characterized by having a step of offset distance in the direction opposite to the offset direction.

  The present invention also relates to an alignment adjustment method for aligning the focal point of the laser of the laser processing apparatus of the present invention, wherein (a) the focal point of the laser is from an inlet opening of a jet nozzle made of a material that transmits the laser. Moving to a first offset position deviated to form a first image in which the direction of the liquid column is missing on the light receiving member; and (b) a first offset defocused from the inlet opening of the jet nozzle. Moving to a second offset position different from the position to form a second image in which the direction of the liquid column is missing on the light-receiving member; and (c) passing through the first offset position and missing the first image. Find the intersection of the first straight line directed in the direction and the second straight line that passes through the second offset position and directed in the direction of the chipping of the second image, and moves the laser focus to the position of the intersection Let A step of (d) moving the focal point of the laser in the axial direction of the jet nozzle to obtain a range in which the laser image is larger than a predetermined diameter; and (e) a laser at a point intermediate between the obtained ranges. And a step of moving the focal point.

  The present invention also includes a jet nozzle that ejects liquid to form a liquid column, a laser optical system that focuses the laser in the liquid column, and a relative movement mechanism that relatively moves the jet nozzle and the focal point of the laser. In addition, in a laser processing apparatus for processing a workpiece by a laser guided by a liquid jet, an alignment apparatus for aligning the focal point of the laser, a liquid column ejected from a jet nozzle, and a translucent plate that receives the laser The light-transmitting plate is arranged so as to project a laser beam, and has a light-receiving member for aligning the focal point of the laser based on the projected image of the laser.

  According to the alignment adjustment method and apparatus of the present invention and the laser processing apparatus including the alignment adjustment method, laser alignment adjustment can be reliably performed without complicating the configuration of the laser processing head.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
First, with reference to FIG. 1, the laser processing apparatus by 1st Embodiment of this invention is demonstrated. FIG. 1 is a diagram showing a configuration of the entire laser processing apparatus according to the present embodiment.

As shown in FIG. 1, a laser processing apparatus 1 according to a first embodiment of the present invention includes a laser processing head 2, a laser optical system 4 for condensing a laser at a predetermined position in the laser processing head 2, and this A laser light source 6 that causes a laser to enter the laser optical system 4 and a pressure pump 8 that sends high-pressure water to the laser processing head 2 are provided.
The laser processing apparatus 1 also includes an alignment apparatus 10 for aligning the focal point of the laser emitted from the laser optical system 4. Further, the laser processing apparatus 1 includes a controller 14 that controls the laser light source 6, the pressure pump 8, and the alignment apparatus 10.

Further, the laser processing head 2 includes a head main body 16 and a jet nozzle 18 attached to the head main body 16.
The laser optical system 4 is configured to guide the laser emitted from the laser light source 6 to the laser processing head 2 and condense the laser at the entrance opening of the jet nozzle 18. The laser focused on the inlet opening of the jet nozzle 18 by the laser optical system 4 repeats total reflection in the water column (liquid column) ejected from the jet nozzle 18 and reaches the workpiece (not shown) by the water column. Led.

  The laser optical system 4 is supported with respect to the laser processing head 2 by a relative movement mechanism 12. By this relative movement mechanism 12, the focal point of the laser emitted from the laser optical system 4 can move in the axial direction (Z-axis direction) of the jet nozzle 18 and a plane (XY plane) orthogonal to the axial line of the jet nozzle 18. It is configured. The relative movement mechanism 12 is controlled by a control signal from the controller 14, and is configured to move the focal point of the laser to a predetermined target focal position.

  The laser light source 6 is configured to generate a laser having a predetermined intensity based on a control signal from the controller 14. In this embodiment, a green laser is used as the laser.

  The pressurizing pump 8 is configured to pressurize water to a predetermined pressure based on a control signal from the controller 14 and flow the water into the head main body 16 of the laser processing head 2. The water fed into the head main body 16 is ejected from the jet nozzle 18 to form a water column.

  The head main body 16 has a liquid supply chamber 16a formed therein, and a liquid supply passage 16b is formed so as to communicate with the liquid supply chamber 16a. Further, a jet nozzle receiving recess is formed at the bottom of the liquid supply chamber 16a so as to communicate with the liquid supply chamber 16a, and the jet nozzle 18 is disposed therein. Further, a window member 16 c for transmitting the laser emitted from the laser optical system 4 and guiding it to the inlet opening of the jet nozzle 18 is attached to the upper end of the liquid supply chamber 16 a. The water sent from the pressurizing pump 8 flows into the liquid supply chamber 16a through the liquid supply passage 16b and is ejected from the jet nozzle 18.

  The jet nozzle 18 is a substantially cylindrical member, and a nozzle hole oriented in the vertical direction is formed on the central axis thereof. The nozzle hole includes a cylindrical portion 18a having a small diameter and extending in a cylindrical shape, and a conical portion that is continuous with the cylindrical portion 18a and whose diameter is expanded toward the downstream side. In addition, the diameter of the jet nozzle 18 shall mean the diameter of the cylindrical part 18a. The jet nozzle 18 is disposed in the jet nozzle receiving recess of the head main body 16.

  The alignment apparatus 10 is arranged below the laser processing head 2 during alignment adjustment of the laser processing apparatus 1 and is configured to output a signal necessary for aligning the focal point of the laser to the controller 14. As shown in FIG. 1, the alignment apparatus 10 reflects a liquid column ejected from a jet nozzle 18 and a glass plate 20 that is a translucent plate that receives the laser, and reflects the laser beam transmitted through the glass plate 20 in a predetermined direction. A mirror 24, a screen 24 that is a light receiving member disposed so that a laser beam transmitted through the glass plate 20 is projected through the mirror 22, and an imaging unit that captures an image of the laser formed on the screen 24. And a certain CCD camera 26.

  The glass plate 20 is disposed substantially horizontally below the laser processing head 2 and is configured to receive a water column ejected in a substantially vertical direction and a laser guided thereby. In addition, when processing a workpiece by the laser processing apparatus 1, the alignment apparatus 10 is moved to another position, and the workpiece is disposed at a position where the glass plate 20 is disposed in FIG. Further, when the alignment apparatus 10 is used, a laser having a lower output than that during laser processing is emitted from the laser light source 6.

  The laser and jet that have entered the glass plate 20 are separated into laser and water by the glass plate 20. That is, the laser passes through the glass plate 20 and passes through the alignment device 10, and the water is blocked by the glass plate 20 and flows down to the outside of the alignment device 10. In the present embodiment, a glass plate is used as the translucent plate. However, a plastic plate or the like can be used as long as it is capable of blocking the liquid and transmitting the laser without being processed by a low-power laser. A member can be used.

  The mirror 22 is built in the alignment apparatus 10 and is disposed below the glass plate 20. The mirror 22 is oriented at an angle of about 45 ° with respect to the vertical axis, and is arranged so as to reflect the laser beam that has passed through the glass plate 20 and is incident in the substantially vertical direction substantially in the horizontal direction.

  The screen 24 is configured to receive the laser beam transmitted through the glass plate 20 through the mirror 22 and is arranged substantially in the vertical direction. The screen 24 can be formed of a member that attenuates the intensity of the laser and does not cause unnecessary reflection. In the present embodiment, the screen 24 is made of ground glass. The laser incident on the screen 24 forms an image, and this laser image has various shapes and patterns depending on the position of the focal point of the laser.

  The CCD camera 26 is provided in the alignment apparatus 10 so as to capture an image of a laser formed on the screen 24. Data of an image captured by the CCD camera 26 is sent to the controller 14. Further, the alignment apparatus 10 can also be configured so that the laser beam transmitted through the glass plate 20 or the laser beam reflected by the mirror 22 is directly imaged by the CCD camera 26. In this case, since an image is directly formed on the image sensor (CCD) built in the CCD camera 26, the image sensor functions as a light receiving member.

  The controller 14 is configured to operate the laser light source 6, the pressure pump 8, and the relative movement mechanism 12, perform laser focus alignment, or process a workpiece. Specifically, the controller 14 includes an input / output interface for various signals, a memory, a microprocessor, a program for operating these, and the like. Further, the controller 14 functions as an alignment control means when performing the alignment of the laser focus.

  Next, an alignment adjustment method in the laser processing apparatus 1 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing a procedure for adjusting alignment in the laser processing apparatus 1 of the present embodiment. FIG. 3 is a graph showing the relationship between the amount of misalignment in each direction and the laser power reaching the glass plate 20 when the nozzle hole diameter is 100 μm. Further, FIGS. 4 to 10 show a schematic view of the laser passing through the nozzle hole of the jet nozzle 18 and an image of the laser formed on the screen 24. FIG.

  Note that the laser processing apparatus 1 of the present embodiment is configured to form an image on the screen 24 after the laser transmitted through the glass plate 20 is reflected by the mirror 22 as shown in FIG. However, the mirror 22 is simply arranged to change the direction of the laser and can be omitted. Accordingly, in the following description, it is assumed that the laser transmitted through the glass plate 20 is directly incident on the screen 24 without passing through the mirror 22. However, the alignment adjustment method described below is exactly the same when the mirror 22 is used. Can be applied.

  FIG. 2 is a flowchart showing a procedure for aligning the focus of the laser to a predetermined target focus position in the laser processing apparatus 1 of the present embodiment. In the present embodiment, the target focal position is set at the intersection of the inlet opening surface 18b of the jet nozzle 18 and the central axis of the cylindrical portion 18a.

  First, in step S1 of FIG. 2, the controller 14 sends a signal to the relative movement mechanism 12 so that the focal point of the laser emitted from the laser optical system 4 is closer to the outlet side than the inlet opening surface 18b of the jet nozzle 18, that is, the jet. The nozzle 18 is moved a predetermined distance below the upper end surface. At this time, the position of the focal point of the laser in the horizontal plane may be any position near the nozzle hole of the jet nozzle 18. The predetermined distance for moving the focal point of the laser is selected so that the spot diameter DS (FIG. 4A) of the laser formed on the entrance opening surface 18b is larger than the diameter of the cylindrical portion 18a. In the present embodiment, the laser spot diameter DS is increased by moving the focal point of the laser below the inlet opening surface 18b of the jet nozzle 18, but the focal point of the laser is moved upward. Accordingly, the laser spot diameter DS may be increased.

  In this state, as shown in FIG. 4 (a), the water in the range of the angle θ1 among the lasers emitted from the laser optical system 4 passes through the jet nozzle 18 and is injected from the jet nozzle 18. Led by. The water column ejected from the jet nozzle 18 hits the glass plate 20, the water is blocked by the glass plate 20, and only the laser passes through the glass plate 20 and enters the alignment apparatus 10. The laser beam that has passed through the glass plate 20 is projected onto the screen 24 while spreading by the numerical aperture NA, that is, spreading at an angle θ1.

  As a result, a laser image as shown in FIG. 4B is formed on the screen 24. Accordingly, the diameter of the laser image on the screen 24 is proportional to the angle θ1. The laser image on the screen 24 is picked up by the CCD camera 26, and the image data is sent to the controller 14 every moment.

  Next, in step S2, the controller 14 sends a signal to the relative movement mechanism 12 to fix the position of the laser optical system 4 in the Z-axis direction (the position of the jet nozzle 18 in the axial direction) while maintaining the XY plane (jet nozzle). The laser optical system 4 is scanned within a plane perpendicular to the axis 18), that is, within a plane parallel to the entrance opening surface 18b. The image of the laser image at each position is sent to the controller 14 from time to time, and the controller 14 searches the position where the diameter of the laser image is the smallest, and moves the laser optical system 4 to that position (FIG. 5A )). That is, the controller 14 sequentially analyzes the image data sent from the CCD camera 26, specifies the position of the laser optical system 4 where the diameter of the laser image is the smallest, and moves the laser optical system 4 to that position. .

  As shown in FIG. 5A, in the state where the focal point of the laser is on the central axis of the cylindrical portion 18a of the jet nozzle 18, only the laser in the range of the angle θ2 passes through the nozzle hole and passes through the glass plate 20. The spread laser spreads at an angle θ2. At this time, the diameter of the laser image formed on the screen 24 is the smallest as shown in FIG. Thereby, a position where the focal point of the laser and the central axis of the cylindrical portion 18a of the jet nozzle 18 are aligned is obtained.

  Next, in step S3, the controller 14 raises the laser optical system 4 while fixing the positions of the laser optical system 4 in the X-axis direction and the Y-axis direction, and the laser image formed on the screen 24 is the largest. Search for a position. That is, the controller 14 sequentially analyzes the image data sent from the CCD camera 26, specifies the position in the Z direction of the laser optical system 4 where the diameter of the laser image is the largest, and the laser optical system 4 at that position. Move. As shown in FIG. 6A, when the focal point of the laser is in the vicinity of the inlet opening surface 18b of the jet nozzle 18, the laser in the range of the angle θ3 that is the entire laser emitted from the laser optical system 4 is injected into the nozzle hole. The laser beam that has passed through and transmitted through the glass plate 20 spreads at an angle θ3. The laser transmitted through the glass plate 20 spreads at an angle θ3, and a laser image having the largest diameter is formed on the screen 24 as shown in FIG.

  However, the diameter of the laser image formed on the screen 24 is substantially constant within a predetermined range in which the laser focus is in the vicinity of the entrance opening surface 18b. This is also apparent from FIG. 3C, which shows the relationship between the amount of misalignment in the Z direction and the intensity of the laser that passes through the jet nozzle 18. This is greatly different from the influence of the misalignment in the X-axis direction and the Y-axis direction shown in FIGS. 3A and 3B on the intensity of the laser passing through the jet nozzle 18.

  As shown in FIGS. 7A to 7C, this phenomenon is caused by the fact that the focal point of the laser is on the entrance opening surface 18b as shown in FIGS. 7A and 7C. This is because the entire laser can pass through the jet nozzle 18 even when the focus position is shifted up and down. Therefore, it is difficult to accurately align the focal point of the laser on the entrance opening surface 18b based on the position where the diameter of the laser image formed on the screen 24 is maximized.

  Next, in step S4, the controller 14 stores in the memory the current X-axis and Y-axis positions where the laser focus and the central axis of the cylindrical portion 18a of the jet nozzle 18 are aligned. Next, the controller 14 moves the laser focus by a predetermined offset distance in the X-axis direction, which is a predetermined offset direction. In the present embodiment, the offset distance is set to be equal to the radius of the cylindrical portion 18 a of the jet nozzle 18. Accordingly, the focal point of the laser is moved on the circumference of the cylindrical portion 18a. The offset direction can be set in any direction in a plane parallel to the inlet opening surface 18b in addition to the Y-axis direction.

  Next, in step S5, the controller 14 raises and lowers the laser optical system 4 while fixing the positions of the laser optical system 4 in the X-axis direction and the Y-axis direction, and an image of the laser formed on the screen 24 is obtained. Search for the darkest position. As shown in FIGS. 8A and 8C, when the focal point of the laser is above or below the inlet opening surface 18b of the jet nozzle 18, as shown in FIGS. The image of the laser formed on 24 becomes brighter. On the other hand, as shown in FIG. 8B, when the focal point of the laser is on the entrance opening surface 18b, the image of the laser formed on the screen 24 as shown in FIG. Get dark.

  This phenomenon can be explained as follows. First, it is considered that the amount of laser light passing through the jet nozzle 18 increases as the proportion of the area of the laser spot formed on the entrance opening surface 18b that overlaps the cylindrical portion 18a increases. . However, in practice, the diameter of the liquid column ejected from the jet nozzle 18 is slightly smaller than the diameter of the cylindrical portion 18a due to contraction, as indicated by an imaginary line in FIG. For this reason, the laser incident on the peripheral portion of the cylindrical portion 18a (the outer portion of the imaginary line) is not guided by the liquid column. Here, when FIGS. 8A to 8C are compared, when the focal point of the laser is on the entrance opening surface 18b and the spot diameter of the laser is small as shown in FIG. 8B, the cylindrical portion 18a. As a result, the amount of laser light incident on the peripheral portion of the laser beam and the laser beam incident on the outside of the cylindrical portion 18a increase, and as a result, the amount of laser light guided by the liquid column decreases, and the image of the laser formed on the screen 24 becomes dark. It is considered to be.

  Finally, in step S6, the controller 14 returns the laser optical system 4 to the positions in the X axis and Y axis directions stored in the memory in step S4. That is, the controller 14 moves the focal point of the laser by an offset distance in a direction opposite to the offset direction moved in step S4. Thereby, as shown in FIG. 10A, the focus of the laser is aligned with a predetermined target focus position. At this time, an image shown in FIG. 10B is formed on the screen 24.

  According to the laser processing apparatus of the first embodiment of the present invention, the focal point of the laser is aligned with the target focal position based on the laser image on the screen, so that the configuration of the laser processing head is not complicated. Laser alignment can be reliably adjusted.

  Moreover, according to the laser processing apparatus of this embodiment, since the image of the laser projected on the screen is imaged by the CCD camera, alignment can be performed based on the imaged image.

  Furthermore, according to the laser processing apparatus of the present embodiment, the controller controls the relative movement mechanism to move the laser focus to the target focus position, so that alignment can be performed automatically.

  In the above-described embodiment, after step S2 in FIG. 2, the laser optical system 4 is moved in the Z-axis direction to search for the position where the laser image becomes the largest (step S3), but this procedure is omitted. You can also That is, step S4 may be executed without executing step S3 after executing step S2 in FIG.

  Further, in the above-described embodiment, the laser optical system 4 is moved as the predetermined offset distance by the distance equal to the radius of the cylindrical portion 18a in step S4 of FIG. 2, but the offset distance is the same as that of the cylindrical portion 18a. The distance may be approximately the same as the radius, and is not necessarily equal to the radius.

  However, in order to align the focal point of the laser more reliably, the procedure of step S3 in FIG. 2 may be executed so that the offset distance is substantially equal to the radius of the cylindrical portion 18a.

  Next, a laser processing apparatus according to the second embodiment of the present invention will be described with reference to FIGS. The laser processing apparatus of this embodiment differs from the first embodiment described above in the procedure for aligning the focal point of the laser. Accordingly, here, only the points of the present embodiment that are different from the first embodiment will be described, and description of similar points will be omitted. FIG. 11 is a schematic diagram illustrating the principle of the alignment adjustment method of the present embodiment. FIG. 12 is a flowchart showing the procedure of the alignment adjustment method in the present embodiment.

  In the present embodiment, as the material of the jet nozzle 18, a hard material that transmits a laser such as diamond or sapphire is used. In this case, as shown in FIG. 11, the laser reaches the glass plate 20 even when the focus of the laser deviates from the nozzle hole of the jet nozzle 18, and a laser image is formed on the screen 24. In addition, a chip 100 as shown in FIG. 11 occurs in this laser image. The present inventors have found that the chip 100 is a shadow of the liquid column B located in the vicinity of the laser that has passed through the portion of the jet nozzle 18 that is not a nozzle hole, and the laser image has a chip 100 in the direction in which the nozzle hole is positioned. Found that occurs. The alignment adjustment method of the present embodiment uses this property.

  First, in step S <b> 11 of FIG. 12, the controller 14 forms an image of a laser having a chip as shown in FIG. 11. Since the area where the laser image is chipped is sufficiently wide, the controller 14 can easily form the image where the chip is generated by appropriately moving the laser optical system 4. For example, when the controller 14 moves the focal point of the laser to the first offset position and the laser image as shown in FIG. 13A as the first image is formed on the screen 24, the controller 14 stores the X coordinate x1 and Y coordinate y1 of the focal point of the laser and the direction α1 of the lack of the laser image in the memory. In this case, the center C of the nozzle hole (cylindrical part 18a) passes through the coordinates (x1, y1) of the focal point of the laser, as shown in FIG. 13B, and is a first straight line directed in the direction of α1. Located on L1.

  Further, the controller 14 moves the focal point of the laser to a second offset position different from the first offset position, and displays a laser image as shown in FIG. 14A as the second image on the screen 24. Let it form. The controller 14 stores the X coordinate x2, the Y coordinate y2, and the laser image chipping direction α2 in the memory. In this case, the center C of the nozzle hole (cylindrical portion 18a) passes through the laser focus coordinates (x2, y2) as shown in FIG. 14B, and is a second straight line directed in the direction of α2. Located on L2.

  Next, in step S12, the controller 14 determines the first offset position coordinates (x1, y1), the chipping direction α1, the second offset position coordinates (x2, y2), and the chipping direction α2. The coordinates of the intersection of the first straight line L1 and the second straight line L2 are calculated. The calculated coordinates substantially coincide with the coordinates of the center C of the nozzle hole, and this position is set as a temporary target focal position in the inlet opening surface 18b. Alternatively, three or more images with missing portions may be obtained, and the coordinates of the center C of the nozzle hole may be calculated from the intersection of three or more straight lines corresponding to these images.

  Further, in step S13, the controller 14 moves the laser optical system 4 to move the focal position of the laser to the intersection of the first straight line L1 and the second straight line L2.

  Next, in step S <b> 14, the controller 14 raises and lowers the laser optical system 4 while fixing the positions of the laser optical system 4 in the X-axis direction and the Y-axis direction, so that the laser image formed on the screen 24 is displayed. Detect the diameter.

  FIG. 15 is a graph showing the relationship between the amount of deviation of the focal position of the laser in the Z direction and the diameter of the formed laser image. As shown in FIG. 15, the diameter of the image of the laser formed on the screen 24 becomes a substantially constant large value within a predetermined range with the position where the focal point of the laser coincides with the entrance opening surface 18b as the center.

In step S15, the controller 14 calculates a range A in which the diameter of the laser image formed on the screen 24 is larger than a predetermined diameter D1. Next, the center point of this range is determined as the position where the focal point of the laser coincides with the entrance opening surface 18b.
Finally, in step S16, the controller 14 moves the focal point of the laser by a minute distance on the entrance opening surface 18b.

  FIG. 16 is a diagram showing changes in the laser image when the focal point of the laser is moved by a minute distance in the vicinity of the central axis of the cylindrical portion 18a. When the focus of the laser is somewhat deviated from the central axis of the cylindrical portion 18a, the laser image formed on the screen 24 has a donut shape as shown in FIG. When the focal point of the laser is closer to the central axis than in the case of FIG. 16 (a), the dark portion at the center of the laser image is reduced as shown in FIG. 16 (b). Further, when the focal point of the laser coincides with the central axis of the cylindrical portion 18a, the laser image becomes a circle with no dark portion at the center, as shown in FIG.

  Using this property, the controller 14 searches for two points where the laser image has a similar donut shape, and the midpoint of these points coincides with the central axis of the cylindrical portion 18a. Decide as a point to do. Alternatively, as a modification, a position where the laser image does not become a donut shape may be determined as a point where the focal point of the laser coincides with the central axis of the cylindrical portion 18a.

  According to the laser processing apparatus of the second embodiment of the present invention, the focal point of the laser can be made to coincide with the axis of the jet nozzle only by obtaining at least two laser images.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the above-described embodiment, the image captured by the CCD camera is read by the controller, and the controller automatically performs alignment adjustment by performing image analysis. It may be performed manually by a person. In this case, the user moves the relative movement mechanism while confirming the image captured by the CCD camera on the monitor, and performs alignment adjustment according to the above-described procedure.

  Alternatively, the alignment adjustment can be performed while the user confirms the image formed on the screen instead of the image captured by the CCD camera. In this case, in order to make it easy to confirm the image on the screen, the image can be observed through an appropriate optical system.

  In the embodiment described above, the alignment apparatus is configured as a part of the laser processing apparatus. However, the alignment apparatus may be configured as a unit separate from the laser processing apparatus.

  Furthermore, the alignment adjustment can be performed by appropriately combining the alignment adjustment procedures in the first and second embodiments described above. For example, after aligning the position of the laser focus in the entrance aperture plane in steps S1 and S2 of FIG. 2, the position of the laser focus in the Z-axis direction is aligned in steps S14 and S15 of FIG. Can do.

It is a figure which shows the structure of the whole laser processing apparatus by 1st Embodiment of this invention. It is a flowchart which shows the procedure which adjusts alignment in the laser processing apparatus by 1st Embodiment of this invention. It is a graph which shows the relationship of the shift | offset | difference amount of the alignment of each direction, and the power of the laser which reaches | attains a glass plate. (A) The schematic diagram of the laser which passes the nozzle hole of a jet nozzle, (b) It is a figure which shows the image of the laser formed on a screen. (A) The schematic diagram of the laser which passes the nozzle hole of a jet nozzle, (b) It is a figure which shows the image of the laser formed on a screen. (A) The schematic diagram of the laser which passes the nozzle hole of a jet nozzle, (b) It is a figure which shows the image of the laser formed on a screen. It is a schematic diagram of the laser which passes the nozzle hole of a jet nozzle. It is a schematic diagram of the laser which passes the nozzle hole of a jet nozzle. It is a figure which shows the image of the laser formed on a screen. (A) The schematic diagram of the laser which passes the nozzle hole of a jet nozzle, (b) It is a figure which shows the image of the laser formed on a screen. It is a schematic diagram which shows the principle of the alignment adjustment method in 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the alignment adjustment method in 2nd Embodiment of this invention. (A) The 1st image of the laser formed on a screen, (b) It is a figure which shows the coordinate of the focus of a laser, and the positional relationship of a nozzle hole. (A) The 2nd image of the laser formed on a screen, (b) It is a figure which shows the coordinate relationship of the focus of a laser, and the positional relationship of a nozzle hole. It is a graph which shows the relationship between the deviation | shift amount of the Z direction of the focus position of a laser, and the diameter of the image of the laser formed. It is a figure which shows the change of the image of a laser when the focus of a laser is moved a minute distance near the center axis line of a nozzle hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus by 1st Embodiment of this invention 2 Laser processing head 4 Laser optical system 6 Laser light source 8 Pressure pump 10 Alignment apparatus 12 Relative movement mechanism 14 Controller 16 Head main-body part 16a Liquid supply chamber 16b Liquid supply channel 16c Window Member 18 Jet nozzle 18a Cylindrical portion 18b Entrance opening surface 20 Glass plate (translucent plate)
22 mirror 24 screen (light receiving member)
26 CCD camera (imaging means)
100 chip

Claims (12)

A laser processing apparatus for processing a workpiece by a laser guided by a liquid jet,
A jet nozzle that ejects liquid to form a liquid column;
A laser optical system for condensing the laser in the liquid column;
A relative movement mechanism that relatively moves the jet nozzle and the laser focus so that the focus of the laser can be aligned with a predetermined target focus position with respect to the inlet opening of the jet nozzle;
A liquid column ejected from the jet nozzle and a translucent plate for receiving a laser;
A light receiving member that is arranged so that a laser that has passed through the light transmitting plate is projected, and based on the image of the projected laser, and for aligning the focal point of the laser;
A laser processing apparatus comprising:   The laser processing apparatus according to claim 1, further comprising an imaging unit that captures an image of a laser projected on the light receiving member.   The laser processing apparatus according to claim 2, further comprising an alignment control unit that controls the relative movement mechanism based on an image captured by the imaging unit and moves the focal point of the laser to the target focal position. The alignment control means includes
(A) moving the focal point of the laser in a plane perpendicular to the axis of the jet nozzle, and moving the focal point of the laser on the axis of the jet nozzle;
(B) moving the focal point of the laser in the axial direction of the jet nozzle, and moving the focal point of the laser onto the inlet opening surface of the jet nozzle;
The laser processing apparatus according to claim 3, wherein the laser processing apparatus is configured to execute the following. Step (a) above is
(A1) moving the focal point of the laser in the axial direction of the jet nozzle so that the spot diameter of the laser formed on the inlet opening surface of the jet nozzle is larger than the diameter of the jet nozzle;
(A2) moving the focal point of the laser in a plane perpendicular to the axis of the jet nozzle so that the image of the laser is minimized;
The laser processing apparatus of Claim 4 which has these. The jet nozzle is made of a material that transmits laser, and the step (a) includes:
(A1) moving the focal point of the laser to a first offset position off the entrance opening of the jet nozzle to form a first image lacking the liquid column direction on the light receiving member;
(A2) The second focal point where the direction of the liquid column is missing on the light receiving member is moved to a second offset position different from the first offset position, which is deviated from the inlet opening of the jet nozzle. Forming an image; and
(A3) A first straight line passing through the first offset position and directed in the direction of chipping of the first image and a second straight line passing through the second offset position and directed toward the direction of chipping of the second image. Determining an intersection with the second straight line, and moving the laser focus to the position of the intersection;
The laser processing apparatus of Claim 4 which has these. Step (b) above
(B1) moving the focal point of the laser within a plane perpendicular to the axis of the jet nozzle and a predetermined offset distance in a predetermined offset direction;
(B2) moving the focal point of the laser in the axial direction of the jet nozzle so that the image of the laser is darkest;
(B3) moving the focal point of the laser within the plane orthogonal to the axis of the jet nozzle in the direction opposite to the offset direction, the offset distance;
The laser processing apparatus according to any one of claims 4 to 6, comprising:   The laser processing apparatus according to claim 7, wherein the offset distance is substantially equal to a radius of a nozzle hole of the jet nozzle. Step (b) above
(B1) moving the focal point of the laser in the axial direction of the jet nozzle to obtain a range in which the laser image is larger than a predetermined diameter;
(B2) moving the focal point of the laser to an intermediate point in the determined range;
The laser processing apparatus according to any one of claims 4 to 6, comprising: A method of aligning the focus of the laser of the laser processing apparatus according to claim 1 or 2,
(A) moving the focal point of the laser in the axial direction of the jet nozzle so that the spot diameter of the laser formed on the inlet opening surface of the jet nozzle is larger than the diameter of the jet nozzle;
(B) moving the focal point of the laser in a plane perpendicular to the axis of the jet nozzle so that the image of the laser is minimized;
(C) moving the focal point of the laser in a predetermined offset direction within a plane perpendicular to the axis of the jet nozzle; and
(D) moving the focal point of the laser in the axial direction of the jet nozzle so that the image of the laser is darkest;
(E) moving the focal point of the laser in the plane perpendicular to the axis of the jet nozzle in the direction opposite to the offset direction, the offset distance;
An alignment adjustment method characterized by comprising: A method of aligning the focus of the laser of the laser processing apparatus according to claim 1 or 2,
(A) The focal point of the laser is moved to a first offset position deviated from an inlet opening of the jet nozzle made of a material that transmits the laser, and a first direction in which the direction of the liquid column is missing on the light receiving member. Forming an image of
(B) The second focus position is shifted from the inlet opening of the jet nozzle to a second offset position different from the first offset position, and the direction of the liquid column is missing on the light receiving member. Forming an image; and
(C) a first straight line passing through the first offset position and directed in the direction of chipping of the first image, and passing through the second offset position and directed toward the direction of chipping of the second image. Determining an intersection with the second straight line, and moving the laser focus to the position of the intersection;
(D) moving the focal point of the laser in the axial direction of the jet nozzle to determine a range in which the laser image is larger than a predetermined diameter;
(E) moving the focus of the laser to an intermediate point in the determined range;
An alignment adjustment method characterized by comprising: A liquid comprising a jet nozzle that ejects a liquid to form a liquid column, a laser optical system that focuses a laser in the liquid column, and a relative movement mechanism that relatively moves the focal point of the jet nozzle and the laser In a laser processing apparatus for processing a workpiece by a laser guided by a jet, an alignment apparatus for aligning the focal point of the laser,
A liquid column ejected from the jet nozzle and a translucent plate for receiving a laser;
A light receiving member that is arranged so that a laser that has passed through the light transmitting plate is projected, and based on the image of the projected laser, and for aligning the focal point of the laser;
An alignment apparatus comprising: