Laser cutting head

Abstract

The utility model discloses a laser cutting head which comprises a cutting head body and further comprises a light source set, the light source set is installed in the cutting head body and comprises a plurality of active light sources, and the active light sources are arranged based on a preset shape; the number of the half-reflecting mirrors is one or more, and the half-reflecting mirrors are arranged in the cutting head body; and the image acquisition device is arranged in the image acquisition area and is used for acquiring an image of the light beam after the light beam emitted by the active light source passes through the one or more half-reflecting mirrors and reaches the image acquisition area. Compared with a light beam of a single laser module, the large contour of the light source group can easily realize a larger contour, thereby facilitating the improvement of recognition of image changes under the conditions of same lens distortion and focus offset.

Description

[0001] This application claims the priority of Chinese Patent Application CN 2024107237134 with an application date of June 5, 2024.

[0002] This application incorporates the entire text of the above-mentioned Chinese patent application by reference. Technical Field

[0003] This application relates to the field of laser cutting, and more particularly to a laser cutting head. Background Art

[0004] With the development of technology, in the laser cutting industry, the laser processing power has been continuously improved.

[0005] During high-power laser cutting, as the processing time increases, the heat absorbed and accumulated by components such as lenses and lens barrels will also continuously increase. The resulting "thermal lens effect" of the lens itself and the deformation caused by uneven heating of the lens barrel are likely to cause the focal position to shift, making the cutting parameters no longer objective. This situation will seriously affect the cutting quality and reduce the cutting performance.

[0006] In traditional solutions, inside the laser cutting head, by installing a camera or image sensor, the focal shift amount is inferred based on the change amount of the spot image size of the indicating light source emitted by the observation indicating light source. However, since observing the spot of a single indicating light source is easily affected by factors such as unclear spot boundaries, large influence of environmental scattered light on the spot image, irregularity of the original indicating light source spot, and non-fixed spot size, it is difficult to effectively judge the change in the focal shift amount through the contour change of the traditional indicating light source. Utility Model Content

[0007] To solve the above problems, this application proposes a laser cutting head, including a cutting head body, and the laser cutting head further includes:

[0008] A light source group, the light source group is installed inside the cutting head body, and the light source group includes a plurality of active light sources, and the active light sources are arranged based on a preset shape;

[0009] One or more half-reflecting mirrors, which are arranged inside the cutting head body;

[0010] An image acquisition device, which is arranged in the image acquisition area, and is used to acquire the image of the light beam after the active light sources emit light beams, pass through one or more of the half-reflecting mirrors, and reach the image acquisition area.

[0011] In one example, a processing laser light source is arranged inside the cutting head body;

[0012] The light source group is arranged around the output end of the processing laser light source, and the light beam is emitted from top to bottom and enters the laser processing channel.

[0013] In one example, a focusing lens is arranged inside the cutting head body;

[0014] The semi-reflective mirror is arranged below the focusing lens and has a preset angle with the focusing lens;

[0015] The image acquisition area is arranged on the side of the semi-reflective mirror.

[0016] In one example, there are multiple semi-reflective mirrors. Among them, the first semi-reflective mirror is arranged on one side of the output end of the processing laser light source, and the second semi-reflective mirror is arranged below the focusing lens and has a preset angle with the focusing lens;

[0017] One of the light source group and the image acquisition area is arranged on the side of the first semi-reflective mirror, and the other is arranged on the side of the second semi-reflective mirror;

[0018] The light beam of the light source group enters the laser processing channel after being reflected by the first semi-reflective mirror or the second semi-reflective mirror.

[0019] In one example, the light source group is annular, and multiple active light sources in the light source group are evenly distributed.

[0020] In one example, the transmittance of the semi-reflective mirror to the processing laser is higher than a first preset threshold, and the reflectivity to the active light source is higher than a second preset threshold.

[0021] In one example, a projection screen is further arranged in the image acquisition area;

[0022] After the light beam reaches the image acquisition area, it is projected on the projection screen;

[0023] The image acquisition device acquires the image of the light beam on the projection screen.

[0024] In one example, a light intensity sensor is further arranged inside the cutting head body;

[0025] The light intensity sensor is used to acquire the intensity of the scattered light in the cavity of the cutting head body.

[0026] The present application can bring the following beneficial effects to the laser cutting head:

[0027] Influencing factors such as changes in ambient light intensity and changes in the focusing position have a greater impact on the contour recognition of a single spot image, but have a smaller impact on the recognition of the center point of the spot. Moreover, the large contour of the light source group is easier to achieve a larger contour relative to the beam of a single laser module, which is convenient for improving the recognition of image changes under the conditions of the same lens distortion and focus shift. That is to say, during the image acquisition and analysis process, the center position of each spot is relatively less affected by changes in ambient light, clarity, spot size, and beam intensity.

[0028] Relative to the change amount of the contour of each spot itself, the position of the center point of each spot is relatively easy to visually analyze and calculate, and the overall graphic contour fitted by the center points of each spot is relatively stable and clear. Therefore, the method of using the light source group to form an image, fitting out the contour size, and inferring the actual focus position and focus shift amount based on the contour size, calibration data model or calculation for focus compensation has better stability and recognition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0030] Figure 1 It is a schematic diagram of the focus shift of the laser cutting head in the embodiment of the present application;

[0031] Figure 2 It is a schematic diagram of the structure of the laser cutting head in one case of the embodiment of the present application;

[0032] Figure 3 It is a schematic diagram of the structure of the laser cutting head in another case of the embodiment of the present application;

[0033] Among them, 1, collimating mirror; 2, focusing mirror; 3, first position; 4, second position; 5, light source group; 6, first half-reflecting mirror; 7, second half-reflecting mirror; 8, image acquisition device; 9, projection screen. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that the orientation terms such as left, right, up, down, front, and back in the embodiments of the present utility model are only relative concepts to each other or are referenced based on the normal use state of the product, that is, the traveling direction of the product, and should not be considered as restrictive.

[0036] In addition, it should also be noted that the dynamic terms such as "relative movement" mentioned in the embodiments of the present utility model not only refer to the change in position, but also include movements such as rotation and rolling where there is no relative change in position but the state has changed.

[0037] Finally, it should be noted that when a component is referred to as "being located" or "being disposed" on another component, it can be on another component or there may be an intermediate component present at the same time. When a component is referred to as "being connected to" another component, it can be directly connected to another component or there may be an intermediate component present at the same time.

[0038] The following will, with reference to the accompanying drawings, detail the technical solutions provided by the embodiments of the present application.

[0039] As Figure 1 shown, during the actual use of the laser cutting head, the situation of focus shift may occur. Focus shift essentially means that due to the heat accumulation of the lens, the temperature of the lens rises, and the overall curvature of the lens group composed of lenses such as the collimating lens 1 and the focusing lens 2 increases, presenting the characteristics of a convex lens. When focus shift occurs, the focus changes towards the positive focus direction. The greater the increase in curvature, the greater the shift of the focus towards the positive focus direction.

[0040] In Figure 1 , the first position 3 is the theoretical focus position, and the second position 4 is the actual focus position after the lens deforms (the focus has shifted). For the problems existing in the timing compensation, a camera or an image sensor can be installed inside the laser cutting head, and the amount of focus shift can be inferred based on the change in the size of the spot image of the indicating light emitted from the fiber optic crystal head of the laser. Of course, a matching lens and filter can also be added to filter out the light outside the spectrum band of the light source group and eliminate the influence of scattered light, so that the photosensitive element of the camera or the image sensor can more completely observe the entire spot image at the position where it is located.

[0041] However, during the process of observing the spot of a single indicating light source, it is easily affected by factors such as unclear spot boundaries, large influence of environmental scattered light on the spot image, irregularity of the original indicating light source spot, and non-fixed spot size. It is difficult to effectively judge the change in the amount of focus shift by observing the contour change of a single original indicating light spot.

[0042] Moreover, when setting the focus position, the positions of the collimating mirror 1 or the focusing mirror 2 of the laser cutting head are adjustable and variable. Therefore, the observed spot size itself is variable. From the perspective of the image, the edge (also called the contour) of a single spot is easily affected by factors such as the irregularity of the spot of the original indicating light source, its own stray light, and the change in the intensity of ambient scattered light, making it difficult to define the edge change situation.

[0043] Based on this, as Figures 2 to 3 shown, by setting the light source group 5 and relying on the light source group to complete the calculation of the focus offset, the problems brought by a single indicating light source can be solved.

[0044] Inside the cutting head body (not shown in the figure), a light source group 5 is provided. The light source group 5 includes a plurality of active light sources, and the active light sources can actively emit corresponding light beams under control. The active light sources are arranged based on a preset shape, and the shape can be a ring, multiple parallel line shapes, or other irregular shapes, etc. When its shape is a ring, it can be a circular ring, a sector-shaped ring, a rectangular ring, and the multiple active light sources in the light source group 5 can be evenly distributed. For example, it can be multiple active light sources, distributed in a circular ring shape, emitting multiple parallel light beams to form a beam combination similar to a ring.

[0045] Influencing factors such as changes in the intensity of ambient light and changes in the focusing position have a greater impact on the contour recognition of a single spot image, but have a smaller impact on the recognition of the center point of the spot. Moreover, the large contour of the light source group is easier to achieve a larger contour compared to the beam of a single laser module, facilitating the improvement of the recognition of image changes under the conditions of the same lens distortion and focus offset. That is to say, during the image acquisition and analysis process, the central position of each spot is relatively less affected by changes in ambient light, clarity, spot size, and beam intensity.

[0046] Compared with the change amount of the contour of each spot itself, the positions of the center points of each spot are relatively easy to visually analyze and calculate, and the overall graphic contour fitted by the center points of each spot is relatively stable and clear. Therefore, the method of using the light source group to form an image, fitting out the contour size, and inferring the actual focus position and focus offset amount based on the contour size, calibration data model, or calculation for focus compensation has better stability and recognition accuracy.

[0047] In addition, the brightness and output power of each active light source in the light source group are relatively consistent. And the brightness of the active light source can be designed to be fixed or adjustable. The light emitted by the light source group can be parallel or indicating laser at a certain angle according to rules, or it can be a non-laser beam.

[0048] As Figures 2 to 3As shown, a collimating mirror 1 and a focusing mirror 2 are also provided in the cutting head body (not shown in the figure). Generally speaking, the collimating mirror 1 is arranged above the focusing mirror 2. The collimating mirror 1 is mainly used to make the beam emitted by the processing laser light source or the light source group 5 parallel or collimated, ensuring that the beam can be transmitted to the next optical element in a consistent form. The focusing mirror 2 is mainly used to focus the collimated beam onto the focus on the workpiece surface to achieve high-energy-density laser processing.

[0049] One or more semi-reflective mirrors are also provided inside the cutting head body, which can reflect the beam emitted by the light source group, thereby changing the path of the beam.

[0050] As Figures 2 to 3 shown, an image acquisition device 8 is also provided. The image acquisition device 8 is arranged in the image acquisition area. When the active light source in the light source group 5 emits a beam, after passing through one or more semi-reflective mirrors, the beam reaches the image acquisition area, and the image acquisition device 8 acquires the image formed by the beam. The image acquisition device 8 can be arranged inside the cutting head body, and it can be a camera or an image sensor.

[0051] By correspondingly setting the position and angle of the light source group 5, the beam can pass through the lenses (such as the collimating mirror 1 and the focusing mirror 2) that may cause focus shift, and after being reflected by the semi-reflective mirror, it reaches the image acquisition area.

[0052] In one embodiment, as Figure 2 shown, the light source group 5 is arranged around the output end of the processing laser light source. When the light source group is annular, it can be arranged around the processing laser light source, and the beam is emitted from top to bottom and enters the laser processing channel.

[0053] At this time, the number of semi-reflective mirrors can be one, which is arranged below the focusing mirror and is called the first semi-reflective mirror 6 here, and there is a preset angle between it and the focusing mirror. For example, the angle between the two is 45 degrees. Of course, a semi-reflective mirror can also be arranged below the light source group 5 and above the collimating mirror 1, which is called the second semi-reflective mirror 7 here, and whether the second semi-reflective mirror 7 is added can be determined according to requirements. At this time, Figure 3 the multiple mirrors in it are, from top to bottom in sequence: the second semi-reflective mirror 7, the collimating mirror 1, the focusing mirror 2, and the first semi-reflective mirror 6.

[0054] The image acquisition area is arranged on the side of the first semi-reflective mirror 6. When the second semi-reflective mirror 7 is not provided, the beam emitted by the light source group 5 passes through the collimating mirror 1 and the focusing mirror 2, and after being reflected by the first semi-reflective mirror 6, it enters the image acquisition area, and the image acquisition device 8 acquires the beam image in the image acquisition area. Of course, if the second semi-reflective mirror 7 is provided, the light source group 5 enters the collimating mirror 1 after passing through the second semi-reflective mirror 7 and continues to move forward until it reaches the image acquisition device 8.

[0055] As Figure 3 shown, the number of semi-reflective mirrors can also be multiple. Among them, there are a first semi-reflective mirror 6 and a second semi-reflective mirror 7. The first semi-reflective mirror 6 is arranged below the focusing mirror 2 and has a preset angle with the focusing mirror 2, for example, 45 degrees. The second semi-reflective mirror 7 is arranged on one side of the output end of the processing laser light source and above the collimating mirror 1, and has a certain angle with the collimating mirror 1 (for example, 45 degrees).

[0056] One of the light source group 5 and the image acquisition device 8 is arranged on the side of the first semi-reflective mirror 6, and the other is arranged on the side of the second semi-reflective mirror 7. After the light beam of the light source group 5 is reflected by the first semi-reflective mirror 6 or the second semi-reflective mirror 7, it enters the laser processing channel.

[0057] When the light source group 5 is arranged above and the image acquisition device 8 is arranged below, the light beam enters the laser processing channel through the second semi-reflective mirror 7, passes through the collimating mirror 1 and the focusing mirror 2 in sequence, and then reaches the image acquisition area through the first semi-reflective mirror 6.

[0058] When the light source group 5 is arranged below and the image acquisition device is arranged above, the light beam enters the laser processing channel through the first semi-reflective mirror 6, passes through the focusing mirror 2 and the collimating mirror 1 in sequence, and then reaches the image acquisition area through the second semi-reflective mirror 7.

[0059] In addition, the light beam emitted by the light source group 5 can be a group of parallel light beams or non-parallel light beams. For example, it can be at a certain angle with the central axis and diverge inward or outward.

[0060] In one embodiment, after the light beam of the light source group reaches the image acquisition area, the corresponding light beam image is acquired by the image acquisition device (which can be a camera or an image sensor). Among them, the light beam can directly enter the photosensitive element of the camera or the image sensor for shooting. Or, as Figures 2 to 3 shown, a projection screen 9 (the material of which can be a semi-transparent screen, a double-sided projection cloth, a semi-transparent PVC board, etc.) is arranged in the image acquisition area. The light beam forms an image on the projection screen 9, and the image acquisition device 8 observes the light spot caused by the light beam on the projection screen 9 to perform image acquisition and obtain the light beam image. Among them, the image acquisition device 8 and the projection screen 9 can be on the same side of the first semi-reflective mirror 6, or the image acquisition device 8 can also be on different sides of the first semi-reflective mirror 5 from the projection screen 9, and both can realize the acquisition of the light beam image.

[0061] Further, when a projection screen 9 is provided, the light beam irradiated on the screen or the projection cloth can be an image before the focus of the light beam group (indicating that the focus of the light beam is located outside the first half-reflecting mirror 6 and the projection screen 9), or an image after the focus of the light beam group (indicating that the focus of the light beam is located between the first half-reflecting mirror 6 and the projection screen 9). There is no limitation here. As long as the position of the projection screen 9 is fixed and the contour size of the image on the projection screen 9 is greater than a preset value, it can be ensured that when measuring the contour size, due to the change of the actual focus position, the imaging on the projection screen 9 will not alternate between the two cases of before the focus of the light beam group and after the focus of the light beam group, so as to avoid the situation where the calculation of the contour size is incorrect.

[0062] In one embodiment, the active light source and the processing laser light source belong to different spectral bands, and the spectral band of the processing laser light source is higher than that of the active light source. At this time, the light beam emitted by the light source group 5 has a certain transmittance to the collimating mirror 1 and the focusing mirror 2, and the half-reflecting mirror (including the first half-reflecting mirror 6, the second half-reflecting mirror 7 and other half-reflecting mirrors that can be set) has a high transmittance to the processing laser, and its transmittance is higher than the first preset threshold, which will not affect the operation of the processing laser, and has a certain reflectivity to the active light source, and the reflectivity is higher than the second preset threshold, which can realize the reflection of the light beam of the active light source.

[0063] Compared with the single indicating light source in the traditional scheme, adopting the form of a light source group can solve problems such as the single light spot being easily affected and the imaging being irregular. When collecting the light beam contour, taking the shape contour size formed by multiple active light sources in the light source group as the standard can make the collected contour change more accurate, which is more conducive to judging the change of the focus offset amount.

[0064] Based on the laser cutting head provided in the present application, the calculation of the focus offset amount can be realized by corresponding methods.

[0065] Specifically, the method may include the following steps:

[0066] S101: Control the light source group provided inside the laser cutting head to emit a light beam, so that the light beam reaches a preset image acquisition area after passing through one or more half-reflecting mirrors;

[0067] S102: Obtain the light beam image generated by the light beam in the image acquisition area;

[0068] S103: Analyze the light beam image to obtain the contour size of the shape formed by the light beam in the light beam image;

[0069] S104: Based on the mapping relationship between the profile size, the focus setting value, and the actual focus position generated through pre-testing, obtain the actual focus position during the current operation according to the profile size of the beam formation shape and the focus setting value during the current operation.

[0070] S105: Perform focus offset compensation according to the difference between the target focus position and the actual focus position during the current operation.

[0071] In step S103, an image processing unit is pre-set. After the image acquisition device acquires the beam image, it sends the beam image to the image processing unit for processing.

[0072] The image processing unit is a module in the industrial control computer, mainly used for image processing and calculating the profile size. In addition, the industrial control computer also includes other modules, such as a focus compensation calculation module, which is used to calculate the focus offset amount that needs to be compensated and send a control instruction to the laser cutting head to perform focus offset compensation.

[0073] The image processing unit can also be the software and hardware processing part integrated in an embedded programmable camera, or an embedded module integrated with an image sensor. It is a module in the image acquisition device. When transmitting data to the industrial control computer, instead of transmitting the beam image, it transmits the calculated profile size.

[0074] The industrial control computer communicates with the image acquisition device in a bus manner to transfer image data. For example, it uses an Ethernet bus to transfer data according to the GigE interface.

[0075] Each beam is presented in the form of a light spot in the beam image. Generally speaking, the preset shape corresponding to the light source group can also be correspondingly reflected in the beam image. Therefore, the preset shape in the preset image is usually a regular shape. Taking the preset shape as a ring as an example, during the image analysis process, obtain the position of the center point of each light spot, and then fit the positions of the center points of each light spot into a total profile. When the preset shape is a ring, the finally obtained profile is a circle. At this time, calculate its profile size. The profile size is related not only to the installation position and installation angle of the light source group, but also to each lens inside the laser cutting head.

[0076] In step S104, generally speaking, in the case of no focus offset, that is, when the focus setting value is the same as the actual focus position, as the focus setting value changes, the profile size will also change accordingly. And when there is focus offset, as the focus setting value changes, the actual focus position will also change accordingly. At this time, due to the change of the actual focus position, the profile size will also change accordingly. Therefore, there is a corresponding mapping relationship among the three, and one of them can be obtained based on the other two.

[0077] Pre-generate the mapping relationship among the pre-set contour size, focus setting value, and actual focus position. During the current working process, based on image analysis, the contour size formed by the light beam has been obtained, and the focus setting value is pre-set before work. Therefore, the actual focus position can be inferred based on the mapping relationship.

[0078] Specifically, the generation of the mapping relationship can be completed through multiple rounds of testing. During each round of testing, first, for a single focus setting value, set the corresponding light emission duration and intermittent duration in the periodic light emission. Periodic light emission means that light is continuously emitted during the light emission duration and then stops emitting during the intermittent duration to complete one cycle of light emission.

[0079] Process the laser light source and conduct laser processing tests in a periodic light emission manner to simulate the actual working conditions until the test parameters are stable. The test parameters include the lens temperature (including the problems corresponding to the collimating lens and focusing lens respectively), the degree of lens deformation, and the focus offset. The test parameters being stable means that when continuing to perform periodic light emission, the test parameters no longer change or the change amplitude is very low, lower than the preset amplitude.

[0080] Obtain the actual focus position and contour size in the current state. Among them, the contour size has been obtained above, and the actual focus position can be obtained based on various methods. For example, under the above conditions, during the multi-cycle "periodic" light emission process, corresponding measures are briefly inserted to determine the actual focus position.

[0081] Specifically, the corresponding measures can include:

[0082] Measure 1, blue spark method dot shooting method. When at the positive focus, the nozzle can be removed, and by blowing air, the pulsed laser is hit on the stainless steel plate, and the cutting head is moved up and down until the blue spark is the focus.

[0083] Measure 2, thin plate slit method. Cut the thinnest slit that can be obtained by cutting a thin plate to obtain the focus position. This measure can only be used for negative focus cutting calibration.

[0084] Measure 3, beam analysis method. Observe the light beam using a beam analyzer to obtain the focus position. During the observation process, the nozzle, ceramic ring, and even the bottom module can be removed to facilitate the observation of the entire light beam.

[0085] Measure 4, plastic plate inclined plate pulling method. Horizontally pull a plastic plate at a certain angle to the vertical axis and find the minimum point of the light beam as the focus.

[0086] Measure 5, plastic plate printing method. Move the laser cutting head up and down, and the light beam is printed on the plastic plate. Take the smallest printing diameter as the focus. This measure can only be used for negative focus cutting calibration.

[0087] At this time, a focus setting value is set. When the light is emitted periodically and the continuous light emission duration within each period is fixed, the intermittent duration within each period remains unchanged. After multiple periods, the focus offset tends to be stable. By gradually adjusting the intermittent duration of the periodically emitted light, the focus offset can be gradually changed. After changing the intermittent duration, repeat the laser processing test until the actual focus positions and contour sizes corresponding to all focus offsets (from 0 to the maximum value) under the current single focus setting value are obtained to generate the mapping relationship corresponding to the current single focus setting value.

[0088] In the mapping relationship, as the light emission duration in the periodic light emission increases and the intermittent duration decreases, the focus offset increases.

[0089] Specifically, when the light emission duration of the periodically emitted light is short and the intermittent duration is long enough, the lens temperature is always not high, and usually there is no focus offset. When the light emission duration of the periodically emitted light is fixed and the intermittent duration is short enough, after multiple periods, the heat of the lens accumulates, the lens temperature rises, and the focus offset occurs, that is, an increasing process from none to some.

[0090] When the intermittent duration is zero (at this time, the state of the laser cutting head is continuous light emission), after multiple periods, the lens temperature can rise to the highest, the lens curvature changes to the largest, and the focus offset increases to the largest.

[0091] Under the condition that the focus setting value and the intermittent duration are fixed, after multiple periods, both the lens temperature and the deformation amount tend to be stable, and the focus offset is basically stable. Under each focus setting value, fix an intermittent duration. After multiple periods, a stable contour size can be obtained, and the actual focus position and focus offset corresponding to this contour size under this focus setting value.

[0092] For example, the continuous light emission time T1 and the intermittent duration T2. One period T = T1 + T2. Under the conditions of the current focus setting value and the intermittent duration, continuously test a sufficient number of periods because the lens temperature can tend to be stable and the focus offset can tend to be stable. Under this focus setting value, as long as the number of test periods is sufficient, the larger the intermittent duration T2, the closer the focus offset is to the minimum value 0; the smaller the intermittent duration T2, the closer the focus offset is to the maximum value.

[0093] Therefore, by adjusting the value of the intermittent duration T2, the focus offset is gradually changed from 0 to the maximum value. And by extension, under all focus setting values, the focus offset can be gradually changed by adjusting the value of the intermittent duration T2.

[0094] Finally, change the focus setting value and continue the calibration until the mapping relationships corresponding to all focus setting values are generated, thus obtaining the mapping relationship among the focus setting value, the contour size, and the actual focus position. Generate an association list and store it.

[0095] In step S105, according to the difference between the target focus position in the current work and the actual focus position, perform focus offset compensation.

[0096] Based on the mapping relationship (also known as the calibration relationship) in the above text, the actual focus position has been obtained based on the focus setting value and the contour size.

[0097] At this time, according to the user's processing parameters, obtain the target focus position required by the user (that is, the actual focus position under the user's processing parameters without focus offset). According to the difference between the target focus position and the actual focus position, calculate the offset amount (also the focus offset amount) that needs to be compensated.

[0098] According to the focus setting value, calculate the difference between it and the focus offset amount to obtain the focus setting value that needs to be updated next, thereby completing the update of the focus setting value. Use the updated focus setting value as the re-adjusted user processing parameter to achieve focus offset compensation.

[0099] During the real-time compensation process, use the current focus setting value as the input and the current contour size as the feedback to infer the current actual focus position and the focus compensation value.

[0100] During the dynamic adjustment process, the current focus setting value is used as the intermediate process debugging quantity, the current contour size and the current actual focus position are used as the feedback quantities, and the target focus position required by the user processing parameters is used as the target quantity.

[0101] In step S103, when analyzing the beam image, preprocess the beam image. For example, perform image filtering processing. Through median filtering, the gray values of all pixels within a certain area centered on any pixel can be sorted from small to large, and the median value after sorting is used as the gray value of this pixel. Apply non-linear stretching processing. The gray values of background interference pixel points often have a large difference compared with those of their adjacent pixels. Taking the median value after sorting can make this interference pixel have the same gray value as its adjacent pixels, thereby removing the interference and better maintaining the image edge.

[0102] Based on the binarization threshold, perform binarization processing on the preprocessed beam image, and use the threshold processing area segmentation technology to process the spot image. Make full use of the data difference in gray values between the background and the spot in the image. According to the binarization threshold, judge whether the gray value characteristics of each pixel point in the beam image meet the requirements, so as to identify whether the pixel point belongs to the spot area or the background area, thereby generating a binarized image.

[0103] Perform morphological processing on the binarized beam image, such as dilation, erosion, opening operation, and closing operation, to remove the larger noise at the edge of the binarized image and smooth the spot edge.

[0104] For the beam image after morphological processing, determine the center position of the spot presented by each beam in the image. Calculate the minimum circumscribed rotated rectangle of each spot contour, and use the center coordinates of this rectangle as the geometric center of the spot, that is, the center position.

[0105] Fit according to the center positions of all spots to obtain the corresponding contour and determine the contour size corresponding to the contour.

[0106] Based on the center points of each spot, fit the total contour and infer the current focus position. Although the change in the position of the collimating mirror or focusing mirror causes the focus to move, or the focus shifts due to the distortion of the lens caused by high temperature, it can cause changes in the contour of each spot's own imaging. The geometric center points of each spot are relatively clear in the visual image and can be effectively observed. Extracting the center point of the spot from the visual image is less susceptible to interference factors such as ambient light and focusing than extracting the spot contour.

[0107] In the visual image, the total contour size fitted according to the center points of each spot (for example, the total circular contour of the circular spot group generated by the circular light source group in the visual image) is valid data. According to the contour size fitted by the center points of each spot and the current set focus value, the current actual focus position and focus offset can be inferred based on the mapping relationship, so that focus compensation can be performed. When the light source group is circular, the final obtained circular diameter is the contour size. Of course, the area can also be obtained according to the diameter as the contour size.

[0108] Furthermore, in order to better analyze the spot imaging of the light source group, an optical intensity sensor for real-time collecting the scattered light intensity inside the laser cutting head can be installed near the image acquisition area inside the laser cutting head.

[0109] Collect the scattered light intensity inside the laser cutting head cavity through a light intensity sensor, and determine the corresponding binarization threshold based on the scattered light intensity. Before the laser cutting head leaves the factory, a data model of the processing state, scattered light intensity value, and image average brightness value is established in advance. Through this data model, distinguish between the laser processing state and the non-processing state, introduce the scattered light intensity value collected inside the laser cutting head, batch collect the beam image data of the light source group, and obtain the image brightness value, thereby establishing a data model of the processing state, scattered light intensity value, and image average brightness value.

[0110] At this time, through this data model, the image average brightness value can be obtained based on the scattered light intensity value. Generally speaking, the higher the scattered light intensity, the higher the image average brightness. At this time, in the beam image before binarization processing, the binarization threshold needs to be set based on the image average brightness. When the image average brightness is high, the binarization threshold should retain as many pixel points as possible as black, while when the brightness is low, more pixel points should be retained as white as possible, so as to automatically adjust the brightness of the image.

[0111] The above are only the embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the present application.

Claims

1. A laser cutting head, characterized in that: Comprising a cutting head body, the laser cutting head further comprises: A light source group, the light source group is installed inside the cutting head body, the light source group includes a plurality of active light sources, and the active light sources are arranged based on a preset shape; One or more semi-reflective mirrors are arranged inside the cutting head body; The image acquisition device is arranged in the image acquisition area, and is used for acquiring the image of the light beam after the light beam is emitted by the active light source and passes through one or more semi-reflective mirrors and reaches the image acquisition area.

2. The laser cutting head according to claim 1, characterized in that: A processing laser light source is arranged inside the cutting head body; The light source group is arranged around the output end of the processing laser light source, and the light beam is emitted from top to bottom and enters the laser processing channel.

3. The laser cutting head according to claim 2, characterized in that: A focusing lens is arranged inside the cutting head body; The semi-reflective mirror is arranged below the focusing mirror and has a preset angle with the focusing mirror; The image acquisition area is arranged on the side of the semi-reflective mirror.

4. The laser cutting head according to claim 1, characterized in that: There are multiple semi-reflective mirrors, wherein the first semi-reflective mirror is arranged at one side of the output end of the processing laser light source, and the second semi-reflective mirror is arranged below the focusing mirror and has a preset angle with the focusing mirror; One of the light source group and the image acquisition area is arranged on a side of the first semi-reflective mirror, and the other is arranged on a side of the second semi-reflective mirror; The light beam of the light source group enters the laser processing channel after being reflected by the first semi-reflective mirror or the second semi-reflective mirror.

5. The laser cutting head according to claim 1, characterized in that: The light source group is ring-shaped, and a plurality of active light sources in the light source group are evenly distributed.

6. The laser cutting head according to claim 1, characterized in that: The transmittance of the semi-reflective mirror to the processing laser is higher than a first preset threshold, and the reflectance of the semi-reflective mirror to the active light source is higher than a second preset threshold.

7. The laser cutting head according to claim 1, characterized in that: A projection screen is also provided in the image acquisition area; After the light beam reaches the image acquisition area, it is projected on the projection screen; The image acquisition device acquires the image of the light beam on the projection screen.

8. The laser cutting head according to claim 1, characterized in that: A light intensity sensor is also provided inside the cutting head body; The light intensity sensor is used to collect the scattered light intensity in the cavity of the cutting head body.

Images