Reflection prediction device

Abstract

A reflection prediction device for predicting reflection of a laser in a laser machine for machining a workpiece with a laser emitted from a laser head, the reflection prediction device comprising: a machining path acquisition unit for acquiring machining path data including coordinate values and a laser optical axis direction at each machining position on a machining path where the reference point of the laser head moves; a workpiece shape acquisition unit for acquiring workpiece shape data for identifying a workpiece shape that is the surface shape of the workpiece; an irradiation position specification unit for specifying the irradiation position of the laser on the workpiece shape at the machining position on the basis of the machining path data and the workpiece shape data; a reflection calculation unit for calculating a normal direction at the irradiation position on the workpiece shape and calculating the axial direction of reflected light at the irradiation position from the relationship between the normal direction and the laser optical axis direction; and a reflection information output unit for outputting reflection information including the axial direction of the reflection light.

Description

Reflection Predictor

[0001] The present disclosure relates to a reflectance prediction device.

[0002] Laser processing machines are widely used, which process workpieces using a laser emitted from a laser head. Processing efficiency can be improved by using a high-power laser. In recent years, with the spread of laser oscillators, the laser power of laser processing machines has also been increasing.

[0003] Depending on the combination of the laser wavelength and the workpiece material, the laser absorption rate of the workpiece may fall below 10%, resulting in 90% or more of the laser being reflected by the workpiece surface. Under such conditions, the power of the reflected light increases, and if the reflected light strikes peripheral equipment, wiring, etc., it may damage the peripheral equipment. To prevent the reflected light from striking peripheral equipment, it has been proposed to provide an absorbing plate at the tip of the laser head to absorb the reflected light (see, for example, Patent Document 1).

[0004] JP 2012-110945 A

[0005] If an absorbing plate that absorbs reflected light is provided on the laser head, there may be inconveniences such as a reduced degree of freedom in the relative position of the laser head with respect to the workpiece, or difficulty in appropriately positioning the laser head close to an uneven workpiece. If the reflected light during laser processing can be confirmed in advance, it is often possible to prevent the reflected light from entering peripheral equipment by adjusting the laser head position, etc., and this may be possible to avoid the adverse effects of reflected light more effectively than by providing a member that absorbs reflected light.

[0006] A reflection prediction device according to one aspect of the present disclosure is a reflection prediction device that predicts laser reflection in a laser processing machine that processes a workpiece with a laser emitted from a laser head, and includes: a processing path acquisition unit that acquires processing path data including coordinate values ​​and a laser optical axis direction at each processing position on a processing path along which a reference point of the laser head moves; a work shape acquisition unit that acquires work shape data that identifies the workpiece shape, which is the surface shape of the workpiece; an irradiation position identification unit that identifies laser irradiation positions on the workpiece shape at each processing position based on the processing path data and the workpiece shape data; a reflection calculation unit that calculates a normal direction at the irradiation position of the workpiece shape and calculates the axial direction of the reflected light at the irradiation position from the relationship between the normal direction and the laser optical axis direction; and a reflection information output unit that outputs reflection information including the axial direction of the reflected light.

[0007] Fig. 2 is a block diagram showing the configuration of a reflection prediction device according to an embodiment of the present disclosure; Fig. 3 is a schematic perspective view illustrating a laser optical axis and a reflected optical axis in the reflection prediction device of Fig. 1; Fig. 4 is a schematic perspective view illustrating the spread of reflected light in the reflection prediction device of Fig. 1; Fig. 5 is a schematic perspective view illustrating incidence of light on an object in the reflection prediction device of Fig. 1; Fig. 6 is a diagram showing an example of display of reflection information in the reflection prediction device of Fig. 1;

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a block diagram illustrating the configuration of a reflection prediction device 1 according to an embodiment of the present disclosure. Fig. 2 is a schematic perspective view illustrating the laser optical axis and the reflected optical axis in the reflection prediction device 1.

[0009] The reflection prediction device 1 predicts the reflection of a laser (reflected light R) in a laser processing machine that processes a workpiece W with a laser L emitted from a laser head H. Examples of the laser processing machine include a three-dimensional laser processing machine that has three or more linear axes and two or more rotational axes and changes the posture of the laser head or workpiece using the rotational axes, and a laser robot system that combines an industrial robot and a laser head. The reflection prediction device 1 may be integrated with a numerical control device that controls the laser processing machine, or may be integrated with a CAM that provides processing information (processing programs, device parameter settings, etc.) to the laser processing machine, a computer that manages multiple laser processing machines, or a simulator that simulates the operation of the laser processing machine, or may be an independent device.

[0010] The reflection prediction device 1 includes a machining path acquisition unit 11, a workpiece shape acquisition unit 12, an irradiation position identification unit 13, a reflectance acquisition unit 14, a laser information acquisition unit 15, a reflection calculation unit 16, an object setting unit 17, an incidence determination unit 18, and a reflection information output unit 19. The reflection prediction device 1 may be realized by one or more computer devices that have, for example, a memory, a processor, an input / output interface, etc., and that execute appropriate processing programs. Note that the components of the reflection prediction device 1 described above are classifications of the functions of the reflection prediction device 1, and do not necessarily have to be clearly distinguishable in terms of physical configuration and program configuration.

[0011] The machining path acquisition unit 11 acquires machining path data including the coordinate values ​​of each machining position on the machining path P along which the reference point of the laser head H moves and the direction of the laser optical axis. The direction of the laser optical axis can be expressed as a vector. The machining path acquisition unit 11 may acquire the machining path data from a storage device further provided in the reflection prediction device 1, or may acquire the machining path data from an external device. The reference point of the laser head H may be, for example, the focal position of the laser L emitted by the laser head H. The reference point may be acquired by analyzing the machining program of the laser machining machine, or may be created by simulating machining in accordance with the machining program, for example.

[0012] The workpiece shape acquisition unit 12 acquires workpiece shape data that specifies the workpiece shape, which is the surface shape of the workpiece W. The workpiece shape data can be three-dimensional data that represents the surface of the workpiece W with polygons (miniature polygonal planes). The workpiece shape acquisition unit 12 may acquire the workpiece shape data from a storage device that is further provided in the reflection prediction device 1, or may acquire the workpiece shape data from an external device.

[0013] The irradiation position specifying unit 13 specifies the irradiation position S of the laser L on the workpiece shape at the machining position based on the machining path data and the workpiece shape data. When the reference point of the laser head H is the focal position of the laser L, ideally the irradiation position S exists on the machining path P, but the irradiation position S may deviate from the machining path P due to interpolation errors between command points specified in each program, etc. The irradiation position specifying unit 13 converts the machining path P and the workpiece shape, which can be expressed using coordinates in different coordinate systems, into data in the same coordinate system, and specifies the irradiation position S corresponding to the machining position. The machining path P and the workpiece shape are expressed by coordinate data in an orthogonal coordinate system in which the axial directions are aligned, and the intersection of the workpiece shape and the optical axis of the laser L when the offset of the origins of both coordinates is corrected becomes the irradiation position S.

[0014] The reflectance acquisition unit 14 acquires the expected reflectance of the laser L on the workpiece W (the ratio of the power of the reflected light R to the power of the laser L). The reflectance of the laser L mainly depends on the wavelength of the laser L and the material of the workpiece W. Because the wavelength of the laser L is an inherent value of the laser processing machine, the reflectance acquisition unit 14 can be configured to acquire material information of the workpiece W and acquire the reflectance corresponding to the acquired material information of the workpiece W by referring to a preset reference table.

[0015] The laser information acquiring unit 15 acquires laser information including the power of the laser L at the processing position. The laser information may further include information such as the divergence angle of the laser L and the power density distribution in a plane perpendicular to the optical axis of the laser L.

[0016] The reflection calculation unit 16 calculates the normal direction at the irradiation position S of the workpiece shape, and calculates the axial direction of the reflected light R at the irradiation position S from the relationship between the normal direction and the laser optical axis direction. In other words, the reflection calculation unit 16 calculates the axial direction of the reflected light R on the assumption that the laser L is specularly reflected on the surface of the workpiece W. In other words, the axial direction of the reflected light R is set to a direction (vector) that is line-symmetric with the laser optical axis, with the normal at the irradiation position S of the workpiece shape as the symmetry axis. The reflection calculation unit 16 may further calculate the spread range of the reflected light R in accordance with the spread angle of the laser L, as shown in FIG. 3 .

[0017] The object setting unit 17 sets object information that specifies the position of an object B (illustrated in FIG. 4 ) onto which reflected light may be incident. The object information set by the object setting unit 17 may include tolerance information that indicates the tolerance of the incidence of reflected light R. The tolerance information may be information on the function performed by object B, such as a structural component, wiring component, or safety cover, or the material of object B, but may also be information on whether object B allows the incidence of reflected light R, the upper limit of the power density of reflected light R that allows incidence, the upper limit of the power of reflected light R that allows incidence, a rank of the upper limit of the power of reflected light R that allows incidence, etc. Note that equipment designed to be free from problems even if reflected light R is incident, such as equipment having a cover designed to allow incidence of reflected light R, does not need to be set as object B.

[0018] The incidence determination unit 18 determines whether the reflected light R is incident on object B based on the object information and the reflection information. For example, the incidence determination unit 18 may be configured to determine that the reflected light R is incident on object B if the optical axis of the reflected light R intersects with object B. Such a determination can be made using a collision determination algorithm widely used in computer game programming, or the like. The incidence determination unit 18 may determine whether the reflected light R is incident on object B by taking into account the spread range of the reflected light R. Furthermore, the incidence determination unit 18 may switch whether or not to include object B in the incidence determination for reflected light R based on the laser information and tolerance information. When the power of the laser L is low, the computational load can be reduced by excluding object B, which has a relatively high resistance to reflected light R, from the incidence determination target.

[0019] The incidence determination unit 18 may calculate the power density of the reflected light R on the surface of the object B, and determine that the reflected light R is incident on the object B when the calculated power density or power exceeds a predetermined determination threshold. In this case, the incidence determination unit 18 may change the determination threshold in accordance with the tolerance information. For example, electrical cables and resin tubes coated with resin may be damaged by the incidence of reflected light R with a relatively low power, which may cause serious trouble in the laser processing machine. On the other hand, equipment with a metal casing does not cause problems even if reflected light R with a relatively low power is incident. For this reason, by changing the determination threshold in accordance with the tolerance information, only cases where trouble may actually occur are extracted. Note that the power density D [W / m ２ ] and power E [W], where Q [W] is the laser power, K is the reflectivity on the surface of the workpiece W, and A [m ２ ], then D=QK / A and E=QK.

[0020] The reflection information output unit 19 outputs reflection information including the axial direction of the reflected light R. The reflection information may be output as data to another computer or the like, or may be output as image information that can be directly confirmed by the user. The reflection information output by the reflection information output unit 19 may further include not only the optical axis direction of the reflected light R but also the spread range of the reflected light R, so that the range reached by the reflected light R can be confirmed. Furthermore, the reflection information output unit 19 may further output whether or not the reflected light R is incident on the object B, so that the user can easily understand whether or not the reflected light R may cause trouble.

[0021] As illustrated in FIG. 5 , the reflection information output unit 19 may output image information in which lines indicating the axial direction of the reflected light R at each processing position are superimposed on the processing path P. This allows the user to easily grasp changes in the reflected light R due to movement of the processing position. Furthermore, the reflection information output unit 19 may also display a model of the workpiece W to further facilitate the user's understanding. The reflection information output unit 19 may be configured to provide an interface that allows the user to select a processing position or irradiation position S, and to selectively display a line indicating the optical axis direction of the reflected light R at the processing position or irradiation position S selected by the user.

[0022] The reflection prediction device 1 having the above configuration can confirm the direction of reflected light R in laser processing in advance, and can prevent reflected light R from entering peripheral equipment by adjusting the laser head posture through minor corrections to the processing program. Therefore, unlike when a member that absorbs reflected light R is provided, problems with the laser processing machine caused by reflected light R can be prevented without impairing the degree of freedom in processing.

[0023] The following supplementary note is further disclosed regarding the above-described embodiment and modified examples. (Supplementary Note 1) A reflection prediction device (1) predicts the reflection of a laser in a laser processing machine that processes a workpiece with a laser emitted from a laser head, and includes a processing path acquisition unit (11) that acquires processing path data including coordinate values ​​and a laser optical axis direction at each processing position on a processing path along which a reference point of the laser head moves, a workpiece shape acquisition unit (12) that acquires workpiece shape data that identifies the workpiece shape, which is the surface shape of the workpiece, an irradiation position identification unit (13) that identifies laser irradiation positions on the workpiece shape at each processing position based on the processing path data and the workpiece shape data, a reflection calculation unit (16) that calculates a normal direction at the irradiation position of the workpiece shape and calculates the axial direction of reflected light at the irradiation position from the relationship between the normal direction and the laser optical axis direction, and a reflection information output unit (19) that outputs reflection information including the axial direction of the reflected light.

[0024] (Supplementary Note 2) In the reflection prediction device (1) of Supplementary Note 1, the reflection calculation unit may further calculate a spread range of the reflected light according to a spread angle of the laser, and the reflection information output by the reflection information output unit may further include the spread range of the reflected light.

[0025] (Supplementary Note 3) The reflection prediction device (1) of Supplementary Notes 1 and 2 further includes an object setting unit (17) that sets object information that specifies the position of an object onto which reflected light may be incident, and an incidence determination unit (18) that determines whether or not reflected light will be incident on an object based on the object information and the reflection information, and the reflection information output unit (19) may further output whether or not reflected light will be incident on an object.

[0026] (Supplementary Note 4) The reflection prediction device (1) of Supplementary Note 3 further includes a reflectance acquisition unit (14) that acquires the reflectance of the laser on the workpiece, and a laser information acquisition unit (15) that acquires laser information including the power of the laser at the processing position, and the incidence determination unit (18) may calculate the power density of the reflected light on the surface of the object, and determine that the reflected light is incident on the object when the calculated power density exceeds a predetermined determination threshold.

[0027] (Supplementary Note 5) In the reflection prediction device (1) of Supplementary Note 4, the object information may include tolerance information indicating the tolerance of the incidence of reflected light from the object, and the incidence determination unit (18) may change the determination threshold in accordance with the tolerance information.

[0028] (Supplementary Note 6) In the reflection prediction device (1) of Supplementary Notes 1 to 5, the reflection information output unit (19) may output image information in which a line indicating the axial direction of reflected light at each processing position is superimposed on the processing path.

[0029] Although the present disclosure has been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0030] For example, in the reflection prediction device according to the present disclosure, the reflectance acquisition unit, laser information acquisition unit, object setting unit, and incidence determination unit are optional components and may be omitted.

[0031] REFERENCE SIGNS LIST 1 reflection prediction device 11 machining path acquisition unit 12 workpiece shape acquisition unit 13 irradiation position identification unit 14 reflectance acquisition unit 15 laser information acquisition unit 16 reflection calculation unit 17 object setting unit 18 incidence determination unit 19 reflection information output unit B object H laser head L laser P machining path R reflected light S irradiation position W workpiece

Claims

1. A reflection prediction device that predicts laser reflection in a laser processing machine that processes a workpiece with a laser emitted from a laser head, comprising: a processing path acquisition unit that acquires processing path data including coordinate values ​​and a laser optical axis direction at each processing position on the processing path along which a reference point of the laser head moves; a work shape acquisition unit that acquires work shape data that identifies the workpiece shape, which is the surface shape of the workpiece; an irradiation position identification unit that identifies each laser irradiation position on the workpiece shape at each processing position based on the processing path data and the workpiece shape data; a reflection calculation unit that calculates a normal direction at the irradiation position of the workpiece shape, and calculates the axial direction of the reflected light at the irradiation position from the relationship between the normal direction and the laser optical axis direction; and a reflection information output unit that outputs reflection information including the axial direction of the reflected light.

2. The reflection prediction device according to claim 1, wherein the reflection calculation unit further calculates the spread range of the reflected light according to the spread angle of the laser, and the reflection information output by the reflection information output unit further includes the spread range of the reflected light.

3. A reflection prediction device as described in claim 1 or 2, further comprising: an object setting unit that sets object information specifying the position of an object onto which the reflected light may be incident; and an incidence determination unit that determines whether the reflected light will be incident on the object based on the object information and the reflection information, wherein the reflection information output unit further outputs whether the reflected light will be incident on the object.

4. A reflection prediction device as described in claim 3, further comprising: a reflectance acquisition unit that acquires the reflectance of the laser on the workpiece; and a laser information acquisition unit that acquires laser information including the power of the laser at the processing position, wherein the incidence determination unit calculates the power density of the reflected light on the surface of the object and determines that the reflected light is incident on the object if the calculated power density exceeds a predetermined determination threshold.

5. The reflection prediction device according to claim 4, wherein the object information includes tolerance information indicating the tolerance of the reflected light incident on the object, and the incidence determination unit changes the determination threshold in accordance with the tolerance information.

6. A reflection prediction device according to any one of claims 1 to 5, wherein the reflection information output unit outputs image information in which a line indicating the axial direction of the reflected light at each of the processing positions is superimposed on the processing path.

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