JP5642235B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus having a processing state monitoring function.

  In cutting processing using laser light, generally, a laser beam generated from a laser oscillator is propagated by an optical system, condensed on a workpiece by a processing lens, and a processing gas is supplied by a nozzle arranged on the same axis. In this state, the cutting process is performed by relatively moving the laser beam and the workpiece. Processing conditions to be adjusted at this time include various parameters such as beam mode, output, pulse conditions, processing gas type, processing gas pressure, nozzle diameter, focal position, and distance between nozzle workpieces. The operator needs to appropriately select the above parameters in order to obtain a good cutting process.

  Since parameter selection differs depending on the material, thickness, and cutting shape of the workpiece, it is a complicated and skillful operation. Usually, a processing condition table is provided by the processing machine manufacturer so that even a normal operator can obtain a good cutting process by selecting a good cutting condition determined in advance according to the type of workpiece and processing quality. Is done.

  If the processing conditions are not appropriate, a good cut surface cannot be obtained. For example, typically, gouging that cannot be completely cut, and a phenomenon called burning in the case of excessive heat input occur.

  When gouging or burning occurs, an unusual and intense light emission phenomenon is observed during the cutting process. Therefore, it is possible to respond by stopping the processing machine when a defect occurs by visually monitoring the worker. However, although it is not as noticeable as gouging or burning, in the case of processing defects such as dross adhering to the back surface of the workpiece or the surface roughness of the cut surface being out of regulation, subtle differences are determined by visual inspection during processing. It is difficult to do. In this case, after completion of the cutting process, it is necessary to determine whether the product is non-defective or defective by visually confirming the back surface or the cut surface.

  As with other NC (numerical control) processing devices, laser processing devices are also running at lower running costs and labor savings, and laser cutting processing is being carried out through long unattended continuous operation. Yes. However, during the continuous operation for a long period of time, if there is a situation that requires correction of some processing conditions such as spatter adhesion to the processing lens, a large number of defective cutting members will occur unless the processing conditions are corrected halfway. End up. As a result, material disposal, reworking, or reworking with a grinder or the like is necessary, and a great loss may occur. Accordingly, even in such an unmanned operation, it is necessary for the operator to visually check the processed workpiece to determine whether it is a non-defective product or a defective product, but this increases the work cost.

  Concerning these manned monitoring problems, when performing laser cutting using a laser processing device, use a sound sensor, optical sensor, camera, etc. to determine the quality of the cutting process in order to monitor the status of the processing point. Various methods have been proposed for stopping the processing device or correcting the processing device to more appropriate processing conditions. For example, in Patent Document 1 below, light generated from a processing unit at the time of laser cutting is detected by an optical sensor, a detected light amount level is acquired in advance, and the light amount at the time of good cutting registered in the database of the control device of the processing apparatus It is proposed to compare with the level range. If the detected light amount is outside the light amount level range during good cutting, it is determined that the processing is defective, and the cutting condition is selected from the good cutting conditions registered in the database.

Japanese Patent Laid-Open No. 10-249560

  In Patent Document 1, since the processing head is provided with a sensor for monitoring the light amount from the processing point, it is possible to detect processing defects such as gouging and burning in which the light amount from the processing point changes greatly. However, when the dross adhesion or the cut surface roughness is outside the specified range, the change in the amount of light from the processing point is very small, and it is difficult to discriminate between good and defective products.

  In actual processing, the laser beam absorptance changes due to differences in surface conditions such as rust and dirt on the workpiece, and therefore it is necessary to correct the optimum laser output. However, it is unclear how the processing conditions may be selected only from the database at the time of good cutting in Patent Document 1.

  Furthermore, when the laser processing device is actually operated continuously, the beam diameter and focal position at the processing point will shift due to contamination on optical components such as the processing lens, transmission optical system, and oscillator mirror. It is necessary to sequentially correct the processing conditions. However, it is unclear which processing conditions may be selected only from the database at the time of good cutting in Patent Document 1.

  Therefore, as in Patent Document 1, it is unclear whether the laser output or the beam focal position should be corrected by simply monitoring the amount of light from the processing point using a single sensor.

  In addition, since the sensor signal intensity also changes due to dirt on the optical window of the sensor or a change in sensitivity of the sensor itself, it is difficult to determine the optimum processing condition.

  As described above, in the configuration according to Patent Document 1, even if processing defects such as gouging and burning can be detected, it is difficult to detect processing defects with a small change in light amount.

  An object of the present invention is to provide a laser processing apparatus that can detect even a processing failure with a small change in the amount of light and can reliably determine the quality of the processing state.

In order to achieve the above object, a laser processing apparatus according to the present invention includes a processing head for irradiating a workpiece with laser light,
In a laser processing apparatus comprising a moving mechanism for moving the workpiece relative to the processing head and cutting the workpiece,
A light detection unit for detecting a spatial distribution of light emitted from a processing point of the workpiece when irradiated with laser light in at least two directions;
A signal processing unit for calculating a ratio between the signal intensity detected in the first direction and the signal intensity detected in the second direction;
A storage unit for storing the ratio together with a processing state at the time of laser processing;
Comparing the reference ratio registered in the storage unit with the ratio acquired at the time of actual laser processing, and comprising a determination unit for determining the quality of the processing state,
Light detection unit is a laser irradiation side of the workpiece, it saw including a single optical sensor arranged around the optical axis of the laser beam,
The first direction is a direction in which a processing point is desired from the side with respect to the processing direction of the laser beam,
The second direction is a direction in which a machining point is desired from the rear with respect to the laser beam machining direction .
A laser processing apparatus according to the present invention includes a processing head for irradiating a workpiece with laser light,
In a laser processing apparatus comprising a moving mechanism for moving the workpiece relative to the processing head and cutting the workpiece,
A light detection unit for detecting a spatial distribution of light emitted from a processing point of the workpiece when irradiated with laser light in at least two directions;
A signal processing unit for calculating a ratio between the signal intensity detected in the first direction and the signal intensity detected in the second direction;
A storage unit for storing the ratio together with a processing state at the time of laser processing;
Comparing the reference ratio registered in the storage unit with the ratio acquired at the time of actual laser processing, and comprising a determination unit for determining the quality of the processing state,
The light detection unit is composed of only a single optical sensor arranged around the optical axis of the laser beam on the laser irradiation side of the workpiece,
Laser processing is performed along at least two processing directions intersecting each other, and the signal intensity is detected by the optical sensor in each processing direction, thereby obtaining a spatial distribution of light emitted from the processing point. .

  According to the present invention, the state of the cutting front in the machining state can be monitored by detecting the spatial distribution of light emitted from the machining point in at least two directions and calculating the ratio of each signal intensity. The quality of the processing state can be reliably determined.

It is a block diagram which shows Embodiment 1 of this invention. It is a top view which shows an example of arrangement | positioning of an optical sensor. It is a perspective view which shows the mode of the process point vicinity of a workpiece. FIG. 4 (a) shows a case where the focal position is displaced upward, and FIG. 4 (b) shows a case where the focal position is downward. The case of displacement is shown. It is a graph which shows the signal intensity change of an optical sensor. FIG. 6A shows a processing state when the cutting speed or laser output is changed as compared with the case of good cutting shown in FIG. 3, FIG. 6A shows the case of high cutting speed or low laser output, and FIG. 6B is low. The case of cutting speed or high laser power is shown. It is a block diagram which shows Embodiment 2 of this invention. It is a top view which shows Embodiment 3 of this invention. It is explanatory drawing which shows an example of the correction method at the time of using a some optical sensor. It is a block diagram which shows Embodiment 4 of this invention. It is explanatory drawing which shows an example of the processing method at the time of using a single optical sensor. It is a block diagram which shows Embodiment 5 of this invention. It is a block diagram which shows Embodiment 6 of this invention. It is explanatory drawing which shows an example of the correction method at the time of using two optical sensors. It is explanatory drawing which shows an example of the correction method at the time of using two optical sensors. It is a top view which shows Embodiment 7 of this invention. It is explanatory drawing which shows a mode that a photosensor is rotated. It is explanatory drawing which shows a mode that a photosensor is rotated. It is a graph which shows an example of the time-dependent change of the signal strength of an optical sensor.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention. The laser processing apparatus includes a processing head 3 for irradiating a workpiece 1 with laser light 2 supplied from a laser oscillator (not shown) via a transmission optical system, and a desired direction of the workpiece 1. Or a processing stage 5 for positioning to a desired position. Here, for easy understanding, the normal direction of the processing stage 5 is defined as the Z direction, and the orthogonal directions of the Z direction are defined as the X direction and the Y direction.

  The processing head 3 is a hollow cylindrical member, in which a processing lens 4 for condensing the laser light 2 is disposed, and forms a desired light spot at a processing point 6 of the workpiece 1. The tip of the processing head 3 is formed in a nozzle shape, and has a function of supplying the assist gas toward the workpiece W while the laser light 2 collected by the processing lens 4 passes therethrough. As the assist gas, oxygen, air, nitrogen, argon or the like is generally used, and plays a role of eliminating evaporated gas and preventing dross adhesion.

  The processing stage 5 is connected to an X actuator, a Y actuator, and a Z actuator that independently drive displacements in the X direction, the Y direction, and the Z direction. Each actuator is a controller (non-control) that controls the operation of the entire laser processing apparatus. Controlled). At the time of laser processing, the controller not only provides the three-dimensional position of the processing stage 5, but also, for example, beam mode, beam output, pulse conditions, processing gas type, processing gas pressure, nozzle diameter, focal position, nozzle workpiece distance, etc. Manage and control various parameters.

  In this embodiment, the laser processing apparatus further includes optical sensors 11 and 12, a signal processing unit 21, a storage unit 22, a determination unit 23, and the like.

  The optical sensors 11 and 12 are composed of, for example, a phototransistor, a photodiode, a CCD, and the like, and the spatial distribution of light emitted from the processing point 6 of the workpiece 1 when irradiated with the laser light 2 in at least two directions. It has a function to detect.

FIG. 2 is a plan view showing an example of the arrangement of the optical sensors 11 and 12. The optical sensors 11 and 12 are installed on the laser irradiation side of the workpiece 1 so that the light emitted from the processing point 6 and passing through the processing lens 4 can be received without interfering with the laser light 2. The optical sensor 11 is disposed in a direction in which a machining point is desired from the side, preferably in the YZ plane, with respect to the laser beam machining direction (the -X direction in FIG. 2). On the other hand, the optical sensor 12 is disposed in a direction in which a processing point is desired from the rear with respect to the processing direction of the laser light, preferably in the ZX plane.

  Returning to FIG. 1, the signal processing unit 21 has a function of calculating a ratio Rab (= Ia / Ib) between the signal intensity Ia detected by the optical sensor 11 and the signal intensity Ib detected by the optical sensor 12.

  The storage unit 22 is also connected to the above-described controller. When performing laser processing, the various parameters as described above, the actual processing state (for example, the occurrence of gouging or burning, the presence or absence of dross adhesion, nonstandard specifications) And the like, and the correspondence relationship between the signal intensity ratio Rab and the like are stored in a database.

  The determination unit 23 has a function of comparing the reference ratio RS registered in the storage unit 22 with the ratio Rab acquired during actual laser processing to determine whether the processing state is good or bad. As the reference ratio RS, generally, a signal intensity ratio Rab when it is determined to be a non-defective product is set.

  Note that the signal processing unit 21, the storage unit 22, and the determination unit 23 may be configured by individual hardware, or may be realized as individual software on a single hardware.

  Next, the operation will be described. The workpiece 1 can be cut into a desired machining shape by moving the machining stage 5 in a state where the laser beam 2 is focused on the machining point 6 of the workpiece 1. At this time, a cut groove 8 is formed in the workpiece 1, and light radiation 7 is generated from the vicinity of the machining point 6 by heat radiation or plasma formation.

  As shown in FIG. 2, when the workpiece 1 moves in the X direction, a cutting groove 8 parallel to the X direction is formed. At this time, the optical sensor 11 detects the light radiation 7 from the processing point 6 from diagonally above in the YZ plane and outputs the signal intensity Ia. On the other hand, the optical sensor 12 detects the light radiation 7 from the processing point 6 from the diagonally upper rear side in the ZX plane, and outputs the signal intensity Ib.

  FIG. 3 is a perspective view showing a state near the processing point of the workpiece 1. The laser beam 2 is focused on a processing point of the workpiece 1, and an inclined surface called a cutting front 9 is formed at the tip of the cutting groove 8. The workpiece 1 is melted at the cutting front 9, and a high-temperature ejected product called plume is discharged from the workpiece 1. Since the cutting front 9 and the plume are both hot, they radiate heat.

  Since the plume is located above the surface of the workpiece 1 and generates isotropic radiated light, the amount of light reaching the optical sensors 11 and 12 is approximately the same level. On the other hand, since the cutting front 9 is located in the workpiece 1, a part of the radiated light from the cutting front 9 is blocked by the wall surface of the processing groove 8, and the amount of light reaching the rear optical sensor 12 is In comparison, the amount of light reaching the side optical sensor 11 is small.

  FIG. 3 shows the cutting front 9 at the time of good cutting, and the amount of light reaching the optical sensor 12 changes significantly according to the inclination angle of the cutting front 9. Therefore, by monitoring the signal intensity Ib of the optical sensor 12, it is possible to detect the change of the cutting front 9 due to the cutting condition with high sensitivity.

  FIG. 4 shows a machining state when the focal position is changed as compared with the case of good cutting shown in FIG. 3, FIG. 4 (a) shows a case where the focal position is displaced upward, and FIG. A case where the position is displaced downward is shown. In FIG. 4A, since the beam diameter of the laser beam 2 is enlarged in the workpiece 1, the heat input density is reduced, the width of the cutting groove 8 is increased, and the necessary removal amount is increased. Accordingly, the inclination angle of the cutting front 9 becomes gentle. At this time, since the normal line of the cutting front 9 approaches the optical sensor 12, the signal intensity Ib of the optical sensor 12 increases.

  On the other hand, in FIG. 4B, since the beam diameter of the laser beam 2 becomes smaller in the workpiece 1, the heat input density increases, the width of the cutting groove 8 decreases, and the inclination angle of the cutting front 9 Becomes steep. At this time, since the normal line of the cutting front 9 moves away from the optical sensor 12, the signal intensity Ib of the optical sensor 12 decreases.

  Therefore, when the focal position of the laser beam 2 changes, the signal intensity of the optical sensor 12 changes greatly while the signal intensity of the optical sensor 11 changes relatively slowly. Therefore, it is possible to monitor the change in the focal position of the laser light 2 by comparing the signal intensity Ia of the optical sensor 11 with the signal intensity Ib of the optical sensor 12 and calculating the ratio Ia / Ib between them.

  FIG. 5 is a graph showing changes in signal intensity of the optical sensors 11 and 12. For example, the relationship between the signal intensities of the optical sensor 11 and the optical sensor 12 at the time of good cutting is acquired, and gain adjustment is performed in advance so that both are equal (graph center).

  Thereafter, when the focal position of the laser beam 2 is displaced upward from that during good cutting, the signal intensity Ib of the optical sensor 12 becomes larger than the signal intensity Ia of the optical sensor 11 corresponding to FIG. 4A (Ia < Ib). On the other hand, when the focal position of the laser beam 2 is displaced downward from that during good cutting, the signal intensity Ib of the optical sensor 12 is smaller than the signal intensity Ia of the optical sensor 11 (Ia>), corresponding to FIG. Ib).

  Therefore, the optimum focus position can be reset by adjusting the Z position of the processing stage 5 so that Ia = Ib.

  Up to now, the inclination angle of the cutting front 9 is changed by changing the heat input density depending on the focal position, and as a result, the signal intensity ratio Ia / Ib of the optical sensors 11 and 12 is calculated to calculate the laser light 2 It was shown that the change of the focal position can be monitored and reset to the optimum position. Examples of changing the heat input density include the beam diameter, cutting speed, laser output, etc. in addition to the focal position. The signal intensity ratios Ia / Ib of the optical sensors 11 and 12 are also calculated for these changes. In the following, it is described that monitoring is possible in the same manner.

  FIG. 6 shows a processing state when the cutting speed or the laser output is changed as compared with the good cutting shown in FIG. 3, and FIG. 6A shows a low heat input density, that is, a high cutting speed or a low laser output. FIG. 6B shows a case where the heat input density is high, that is, a low cutting speed or a high laser output. In FIG. 6A, since the amount of heat supplied to the processing point decreases, the width of the cutting groove 8 decreases and the inclination angle of the cutting front 9 becomes gentle. At this time, since the normal line of the cutting front 9 approaches the optical sensor 12, the signal intensity Ib of the optical sensor 12 increases.

  On the other hand, in FIG. 6B, since the amount of heat supplied to the processing point increases, the width of the cutting groove 8 increases and the inclination angle of the cutting front 9 becomes steep. At this time, since the normal line of the cutting front 9 moves away from the optical sensor 12, the signal intensity Ib of the optical sensor 12 decreases.

  Therefore, by comparing the signal intensity Ia of the optical sensor 11 and the signal intensity Ib of the optical sensor 12 and calculating the ratio Ia / Ib between them, not only the focal position change as described above, but also the change in processing speed, Changes in laser output can be monitored. Further, based on these monitoring results, it is possible to reset optimum processing conditions, that is, a focal position, a beam diameter, a processing speed, a laser output, and the like.

  Only the calculation of the signal intensity ratio Ia / Ib of the optical sensor described in the present embodiment determines which parameter should be preferentially adjusted among a plurality of parameters, including the surface condition of the workpiece. Since it cannot be uniquely determined unless it is clear that the parameter has not changed since the time of good cutting, the processing speed priority set in advance is set in consideration of the time speed of change of the signal intensity ratio Ia / Ib. A parameter to be preferentially adjusted is determined from a rule determined by a priority order for each processing operator such as quality priority or processing stability priority.

  In the present embodiment, the case where the optical sensors 11 and 12 are arranged in a plane perpendicular to the optical axis of the laser light 2 and orthogonal to each other has been described. If the influence of the backward radiation light on is small, it does not necessarily have to be orthogonal. The position of the side optical sensor 11 is preferably in the range of 30 ° to 150 °, more preferably in the range of 60 ° to 120 ° with respect to the X direction where the optical sensor 12 is located. Defects can be determined.

  In the present embodiment, the case where the processing head 3 is fixed and the processing stage 5 on which the workpiece 1 is placed moves is described as an example in laser processing. I just need it. For example, a mechanism for moving the machining head 3 with the machining stage 5 fixed may be used, or a mechanism for moving both the machining head 3 and the machining stage 5 may be used.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing Embodiment 2 of the present invention. The laser processing apparatus has the same configuration as that of the first embodiment, but the optical sensors 11 and 12 are arranged outside the processing head 3. In this case, since the light emission 7 from the processing point 6 can be directly observed without being attenuated by the processing lens, high-sensitivity measurement is possible.

Embodiment 3 FIG.
FIG. 8 is a plan view showing Embodiment 3 of the present invention. The laser processing apparatus has the same configuration as that of the first and second embodiments, but uses four optical sensors 11 to 14.

  In the first and second embodiments, since the two optical sensors 11 and 12 are used, when determining whether the processing state is good or bad, one of the optical sensors is behind the processing direction of the laser beam. In other words, it is limited to the two processing directions of -X direction and -Y direction in FIG.

  In the present embodiment, as shown in FIG. 8, the processing point is the origin, the optical sensor 11 in the Y direction, the optical sensor 12 in the X direction, the optical sensor 13 in the −Y direction, and the optical sensor 14 in the −X direction, respectively. doing. As a result, when determining whether the processing state is good or bad, the condition that the optical sensor is positioned rearward with respect to the processing direction of the laser light increases, and a total of four in the X direction, the −X direction, the Y direction, and the −Y direction. The machining state can be determined in one machining direction.

  Here, with respect to the number of optical sensors, the case of two in the first and second embodiments and four in the present embodiment is illustrated, but two or more are sufficient for practical use. By increasing the number of optical sensors, it is possible to increase the number of cutting directions in which pass / fail judgment can be made. Therefore, in actual cutting, it is possible to increase the ratio that can be monitored with respect to the actual cutting length, and pass / fail for more cutting directions. Judgment is possible.

  Note that when a plurality of optical sensors are used, the sensitivity to the light intensity may be different for each optical sensor due to individual differences and installation deviations, and some correction is necessary.

  FIG. 9 is an explanatory diagram showing an example of a correction method when a plurality of optical sensors are used. When the four optical sensors 11 to 14 are respectively arranged in the X direction, the −X direction, the Y direction, and the −Y direction with the processing point as the origin, each optical sensor is positioned behind the processing direction of the laser light. For example, a rectangular cutting path is set. Sensitivity variation can be corrected by performing standardization by gain adjustment or the like so that the signal intensity of each photosensor is the same for each side of the cutting path.

  Since the sensitivity of the optical sensor generally varies with time and has individual differences, the cutting process for the above correction may be carried out periodically, or the cutting in the direction corresponding to each sensor in normal processing. You may always correct | amend by monitoring the signal strength at the time.

Embodiment 4 FIG.
FIG. 10 is a block diagram showing Embodiment 4 of the present invention. The laser processing apparatus has the same configuration as in the first and second embodiments, but uses a single optical sensor 11. The optical sensor 11 is installed so that the light emitted from the processing point 6 and passing through the processing lens 4 can be received without interfering with the laser light 2. Note that the optical sensor 11 may be disposed outside the processing head 3 as in the second embodiment.

  FIG. 11 is an explanatory diagram showing an example of a processing method when a single optical sensor is used. The optical sensor 11 is arranged in the X direction with the processing point as the origin. First, cutting is performed along the −X direction. At this time, the optical sensor 11 is located rearward with respect to the processing direction of the laser light, and can detect the signal intensity Ib. Next, cutting is performed along the Y direction. At this time, the optical sensor 11 is positioned laterally with respect to the processing direction of the laser light, and can detect the signal intensity Ia. Therefore, the signal processing unit 21 can calculate the ratio Rab between the signal intensity Ia and the signal intensity Ib from the single photosensor 11.

  In this embodiment, when a single optical sensor is used, it is impossible to determine good / bad only by cutting in a straight line direction, but by setting the cutting direction to at least two directions, Determination can be made using the signal intensity ratio. For this reason, it is not necessary to correct the sensitivity variation with respect to the light intensity for each sensor, and it is possible to make a pass / fail judgment with high accuracy without being affected by the change in sensitivity of the sensor over time.

Embodiment 5 FIG.
FIG. 12 is a block diagram showing Embodiment 5 of the present invention. The laser processing apparatus has the same configuration as in the first and second embodiments, but a single optical sensor 11 is mounted on the rotation mechanism. The optical sensor 11 is installed so that the light emitted from the processing point 6 and passing through the processing lens 4 can be received without interfering with the laser light 2. Note that the optical sensor 11 may be disposed outside the processing head 3 as in the second embodiment.

  The processing head 3 is provided with a rotary block 32 supported so as to be rotatable around the optical axis of the laser beam 2 and a drive mechanism 31 for driving the rotary block 32 to rotate. As a result, the optical sensor 11 can be positioned at a desired angle around the optical axis of the laser light 2.

For example, when cutting along the −X direction, positioning the optical sensor 11 in the X direction makes it possible to detect from the rear with respect to the processing direction of the laser light, and the signal intensity Ib is obtained. Subsequently, by positioning the optical sensor 11 in the Y direction, it becomes possible to detect from the side with respect to the processing direction of the laser light, and the signal intensity Ia is obtained. Therefore, the signal processing unit 21 can calculate the ratio Rab between the signal intensity Ia and the signal intensity Ib from the single photosensor 11.

  In this embodiment, even when a single optical sensor is used, it is possible to determine good / bad for any cutting direction.

  In the present embodiment, the case where the rotating block 32 on which the optical sensor 11 is mounted is rotated. However, a mechanism that rotates the entire processing head 3 around the optical axis may be used.

Embodiment 6 FIG.
FIG. 13 is a block diagram showing Embodiment 6 of the present invention. The laser processing apparatus has a configuration similar to that of the first and second embodiments, but two optical sensors 11 and 12 are mounted on the rotation mechanism. The optical sensors 11 and 12 are installed so that the light emitted from the processing point 6 and passing through the processing lens 4 can be received without interfering with the laser light 2. Note that, similarly to the second embodiment, the optical sensors 11 and 12 may be disposed outside the processing head 3.

  The processing head 3 is provided with a rotary block 32 supported so as to be rotatable around the optical axis of the laser beam 2 and a drive mechanism 31 for driving the rotary block 32 to rotate. Thereby, the optical sensors 11 and 12 can be positioned at a desired angle around the optical axis of the laser beam 2. The optical sensors 11 and 12 may be arranged in a direction intersecting at an arbitrary angle around the optical axis, but are preferably arranged in directions orthogonal to each other.

For example, when the optical sensor 11 is positioned in the Y direction and the optical sensor 12 is positioned in the X direction, the optical sensor 12 is detected from behind in the laser beam processing direction by cutting along the -X direction. Signal strength Ib is obtained. At the same time, the optical sensor 11 can detect from the side with respect to the processing direction of the laser light, and the signal intensity Ia is obtained. Therefore, the signal processing unit 21 can calculate the ratio Rab between the signal intensity Ia and the signal intensity Ib.

  Note that when a plurality of optical sensors are used, the sensitivity to the light intensity may be different for each optical sensor due to individual differences and installation deviations, and some correction is necessary.

  14 and 15 are explanatory diagrams illustrating an example of a correction method in the case where two optical sensors are used. As shown in FIG. 14, when cutting along the −X direction, the emitted light is detected from the processing point with the optical sensor 11 positioned in the Y direction and the optical sensor 12 positioned in the X direction. Next, as shown in FIG. 15, the rotating block 32 is rotated 90 degrees clockwise, the light sensor 11 is positioned in the X direction, and the light sensor 12 is positioned in the −Y direction. Is detected. The sensitivity variation can be corrected by performing normalization by gain adjustment or the like so that the signal intensities of the individual optical sensors are the same.

  In the present embodiment, by supporting the two optical sensors 11 and 12 so as to be rotatable, it is possible to acquire signal strengths in two directions at the same time in any cutting direction, and it is possible to always determine whether the machining state is good or bad.

Embodiment 7 FIG.
FIG. 16 is a plan view showing Embodiment 7 of the present invention. The laser processing apparatus has a configuration similar to that of the sixth embodiment, but four optical sensors 11 to 14 are mounted on the rotation mechanism. The optical sensors 11 to 14 may be arranged in a direction intersecting at an arbitrary angle around the optical axis, but are preferably arranged in directions orthogonal to each other.

  In the sixth embodiment, since the two optical sensors 11 and 12 are mounted on the rotation mechanism, for example, when the optical sensor 11 is arranged in the Y direction and the optical sensor 12 is arranged in the X direction, as shown in FIG. In order to monitor the cutting direction that intersects the X direction at 45 degrees, it is necessary to rotate the rotating block 32 up to 135 degrees.

  In this embodiment, since the four optical sensors 11 to 14 are mounted on the rotation mechanism, for example, the optical sensor 11 is in the Y direction, the optical sensor 12 is in the X direction, and the optical sensor 13 is in the -Y direction. When the sensors 14 are respectively arranged in the −X direction, as shown in FIG. 18, in order to monitor the cutting direction intersecting with the X direction at 45 degrees, it is sufficient to rotate the rotating block 32 by 45 degrees. . Therefore, a rotation amount of 1/3 is required as compared with the case where two optical sensors are used, the speed of positioning of the optical sensor is increased, and it is possible to always determine whether the optical sensor is good or bad.

  As for the number of optical sensors mounted on the rotation mechanism, one is described in the fifth embodiment, two is described in the sixth embodiment, and four are described in the present embodiment. You may arrange the above optical sensors. In that case, since the angle between the photosensors can be reduced, the determination can be made more constantly. In the above description, the arrangement of the optical sensors is equally divided with respect to the circumference. However, if the cutting direction is limited in advance, the number of sensors may be limited accordingly. In this case, the number of sensors can be reduced, and the circuit and control can be simplified.

Embodiment 8 FIG.
FIG. 19 is a graph showing an example of the change over time of the signal intensity of the optical sensor. The vertical axis represents the signal intensities Ia and Ib of the optical sensors 11 and 12, and the horizontal axis represents time. This graph shows how the signal intensity Ia of the optical sensor 11 decreases while the signal intensity Ib of the optical sensor 12 increases with the passage of time since the introduction of the apparatus under the same processing conditions.

  In the laser processing apparatuses according to Embodiments 1 to 7, it is possible to determine the focal position of the laser light 2 by monitoring the signal intensity ratio Rab (= Ia / Ib) as described above.

  By comparing the determined focal position with the focal position measured in advance under the same machining conditions when the apparatus is introduced, the temporal movement of the focal position in the laser machining apparatus can be measured. This movement of the focal position is mainly caused by contamination of the processing lens 4, that is, when the amount of laser light absorbed by the processing lens 4 is increased and the actual focal length of the processing lens 4 is shortened. .

  Therefore, in the laser processing apparatus according to Embodiments 1 to 7, it is possible to change the focal position following the deterioration caused by the contamination of the processed lens 4 by measuring an appropriate change in the focal position. Therefore, the replacement frequency of the processing lens 4 can be increased. It is also possible to notify the operator of the replacement time of the processing lens 4 by estimating the contamination of the processing lens 4.

  Further, when the processing lens 4 becomes dirty, not only the focal position is moved but also the beam shape is deteriorated. Therefore, it is difficult to maintain a good processing state only by correcting the focal position. Accordingly, since the processing lens replacement time can be detected before the focal position correction amount reaches a value corresponding to the contamination obtained in advance on a trial basis, the occurrence of defective processing can be suppressed.

1 work material, 2 laser light, 3 processing head, 4 processing lens,
5 machining stage, 6 machining point, 7 light emission, 8 cutting groove, 9 cutting front,
11, 12, 13, 14 Optical sensor,
21 signal processing unit, 22 storage unit, 23 determination unit,
31 drive mechanism, 32 rotating block.

Claims (11)

A processing head for irradiating a workpiece with laser light;
In a laser processing apparatus comprising a moving mechanism for moving the workpiece relative to the processing head and cutting the workpiece,
A light detection unit for detecting a spatial distribution of light emitted from a processing point of the workpiece when irradiated with laser light in at least two directions;
A signal processing unit for calculating a ratio between the signal intensity detected in the first direction and the signal intensity detected in the second direction;
A storage unit for storing the ratio together with a processing state at the time of laser processing;
Comparing the reference ratio registered in the storage unit with the ratio acquired at the time of actual laser processing, and comprising a determination unit for determining the quality of the processing state,
Light detection unit is a laser irradiation side of the workpiece, it saw including a single optical sensor arranged around the optical axis of the laser beam,
The first direction is a direction in which a processing point is desired from the side with respect to the processing direction of the laser beam,
The laser beam machining apparatus characterized in that the second direction is a direction in which a machining point is desired from the rear with respect to the laser beam machining direction . A processing head for irradiating a workpiece with laser light;
In a laser processing apparatus comprising a moving mechanism for moving the workpiece relative to the processing head and cutting the workpiece,
A light detection unit for detecting a spatial distribution of light emitted from a processing point of the workpiece when irradiated with laser light in at least two directions;
A signal processing unit for calculating a ratio between the signal intensity detected in the first direction and the signal intensity detected in the second direction;
A storage unit for storing the ratio together with a processing state at the time of laser processing;
Comparing the reference ratio registered in the storage unit with the ratio acquired at the time of actual laser processing, and comprising a determination unit for determining the quality of the processing state,
The light detection unit is composed of only a single optical sensor arranged around the optical axis of the laser beam on the laser irradiation side of the workpiece ,
Laser processing is performed along at least two processing directions intersecting each other, and the signal intensity is detected by the optical sensor in each processing direction, thereby obtaining a spatial distribution of light emitted from the processing point. Laser processing equipment.   The laser processing apparatus according to claim 1, wherein the light detection unit includes an optical sensor that can move around the optical axis of the laser light. Determination unit, a laser machining apparatus according to claim 1 or 2, wherein the determining the focal position during laser processing based on the ratio of the signal strength. 3. The laser processing apparatus according to claim 1, wherein the determination unit determines an appropriate laser output at the time of laser processing based on a ratio of signal intensity. 3. The laser processing apparatus according to claim 1, wherein the determination unit determines an appropriate cutting speed at the time of laser processing based on a ratio of signal intensity. 3. The laser processing apparatus according to claim 1, wherein the laser processing condition is changed when the determination unit determines that the processing state is defective. The laser processing apparatus according to claim 7, wherein a focal position at the time of laser processing is changed among laser processing conditions. The laser processing apparatus according to claim 7, wherein a laser output during laser processing is changed among laser processing conditions. The laser processing apparatus according to claim 7, wherein a cutting speed at the time of laser processing is changed among laser processing conditions. The processing head includes a processing lens for condensing the laser beam,
9. The laser processing apparatus according to claim 8 , wherein contamination of the processing lens is estimated based on a deviation amount between the changed focal position and a predetermined reference value, and the operator is notified of the replacement timing of the processing lens.

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