Metal surface two-dimensional code laser marking method and laser marking machine

Abstract

The application relates to laser marking and provides a metal surface two-dimensional code laser marking method, which comprises the following steps: generating an initial two-dimensional code file; generating a two-dimensional code inverse code according to the two-dimensional code file; adjusting a focusing spot of a laser to be smaller than a theoretical value; filling the two-dimensional code inverse code to generate a processing file; adjusting a laser focus point of the laser to be located on a product surface; positioning the product surface to calculate a processing position; and adopting the laser to perform laser marking on the processing position of the product surface. The application also provides a laser marking machine which comprises a laser, a galvanometer, a lens, a workbench, a camera, a ring light source and an inclined mirror. In the application, the two-dimensional code inverse code is generated according to the two-dimensional code file, and the laser marking is performed after the two-dimensional code inverse code is filled, so that the integrity of the two-dimensional code can be preserved to the maximum extent, the marking efficiency is improved, no metal splashing occurs in the marking process, and the cleaning step is reduced.

Description

Technical Field

[0001] This invention relates to laser marking, and more particularly to a method and machine for laser marking QR codes on metal surfaces. Background Technology

[0002] With the development of science and technology, QR codes are increasingly used in various industries for information identification and product traceability. A QR code is a black-and-white graphic distributed according to a specific geometric pattern on a two-dimensional plane to record data symbols. QR codes can express information simultaneously in both horizontal and vertical directions, thus conveying a large amount of information within a small area. Traditional product surface QR codes often use labeling and inkjet printing technologies. Labeling technology has limited application scenarios, and labels are easily damaged, leading to information loss, resulting in unreadable or incorrect QR codes. Inkjet QR codes are not durable, easily worn, and have complex processes; inkjet printing also poses certain risks to the environment and human health. Therefore, a superior marking process is needed to replace these two technologies. Laser processing has the characteristic of permanence, and it has no consumable consumption and low production costs. It is currently widely used in manufacturing, and more and more industries are adopting lasers to mark QR codes on product surfaces for product traceability, such as marking QR codes on car engines or bearings.

[0003] There are existing examples of marking QR codes on metal surfaces, such as the "Method for Laser Marking Small-Size QR Codes on Aluminum Alloy Surfaces" published by Chinese Patent Publication No. CN109664026A. This method uses a dot-matrix marking mode, allowing QR codes with sizes ranging from 0.5*0.5 to 1.5*0.5 mm² to be marked on aluminum alloy surfaces. However, this patent's dot-matrix marking method results in relatively large dot spacing, failing to completely fill the entire rectangular module, negatively impacting code reading and rating. Furthermore, many precision parts in the 3C industry require even smaller QR codes. Additionally, the dot-matrix power in this invention is 9-10W, which is relatively high, leading to significant heat-affected zones and potential metal spatter and residue on the marked surface. This necessitates cleaning and drying the marked product, making the process cumbersome and increasing the complexity of the pre- and post-marking processes. Moreover, currently, micro QR codes smaller than 0.5mm generally use picosecond lasers. For example, the Chinese patent publication CN 110626086 A, "A method for engraving micro QR codes in glass with laser", uses a picosecond laser to mark 0.1mm QR codes, which is quite expensive. Summary of the Invention

[0004] The purpose of this invention is to provide a method and machine for laser marking QR codes on metal surfaces, which aims to solve the problems of complex and costly existing laser marking processes on metal surfaces.

[0005] This invention is implemented as follows:

[0006] This invention provides a method for laser marking QR codes on metal surfaces, comprising the following steps:

[0007] Generate initial QR code image file;

[0008] Generate the inverse QR code from the QR code image file;

[0009] Adjust the focused spot of the laser to be smaller than the theoretical value;

[0010] Fill in the inverse code of the QR code to generate a processing drawing file;

[0011] The laser focus of the laser is adjusted to be located on the product surface;

[0012] Position the product surface and calculate the processing location;

[0013] Laser marking is performed on the processing positions on the product surface using a laser.

[0014] Furthermore, a standard initial QR code image is generated using the DATAMATRIX QR code generation method.

[0015] Furthermore, the theoretical value of the focused spot is d'. The focused spot d of the laser <d'。

[0016] Furthermore, the fill spacing of the QR code's reverse code is smaller than the focused spot of the laser.

[0017] Furthermore, the metal is stainless steel, and a blue ring light source is used to illuminate the product surface during marking.

[0018] Furthermore, the laser is a fiber laser with a pulse width of 2-8ns, a frequency of 40-60KHz, a power of 0.3-0.5W, a speed of 300-500mm / s, 3-4 pulses per point, and a dotting time of 0.1-0.3ms.

[0019] Furthermore, the generated initial QR code image size is 0.1*0.1-0.5*0.5mm. 2 Furthermore, the size of the reversed QR code is 1.1-1.3 times that of the initial QR code image.

[0020] This invention also provides a laser marking machine, including a laser, a galvanometer, a lens, and a worktable. The laser emits light that passes sequentially through the galvanometer and the lens to the worktable. The machine also includes a camera, a ring light source, and a slanted mirror. The lens of the camera is directly opposite the ring aperture of the ring light source. The light emitted by the ring light source is reflected by the slanted mirror to the worktable, and then reflected by the worktable to the slanted mirror again. The slanted mirror then reflects the light back to the camera.

[0021] Furthermore, it also includes a beam expander located in the optical path between the laser and the galvanometer.

[0022] Furthermore, before processing, based on the theoretical focusing formula of the light spot and the size of the laser exit spot, a suitable magnification of the beam expander is selected so that the actual focused spot size under the lens is smaller than the theoretical value, and a processing drawing is generated based on the reverse code of the QR code generated from the QR code drawing file.

[0023] The present invention has the following beneficial effects:

[0024] In this invention, the reverse code of the QR code is generated first, and then the reverse code is marked using a vector dot marking mode. This maximizes the preservation of the QR code's integrity and improves marking efficiency. Furthermore, the vector dot marking mode requires very little power, and there is almost no metal splatter during the marking process, further eliminating the need for cleaning steps before and after marking. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart illustrating the method for laser marking QR codes on metal surfaces according to an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the initial QR code image file;

[0028] Figure 3 for Figure 2 The inverse of the QR code in the initial QR code image file;

[0029] Figure 4 for Figure 3 Schematic diagram of the structure after the QR code is filled with inverted code;

[0030] Figure 5 This is a schematic diagram of the structure of a laser marking machine provided in an embodiment of the present invention;

[0031] Figure 6 To adopt Figure 1 Photograph of a miniature QR code after laser marking on a metal surface;

[0032] Figure 7 for Figure 6 A photo of a QR code being scanned visually. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] See Figures 1-6 This invention provides a method for laser marking QR codes on metal surfaces, which uses a laser to mark QR codes on metal surfaces, especially for small-sized QR codes, and includes the following steps:

[0035] Generate an initial QR code image file, which will be the target image file for laser marking. Import the generated QR code image file into the laser marking system, or generate the QR code image file directly on the laser marking system. Specifically, the DATAMATRIX QR code generation method can be used to generate a standard initial QR code image file. The size of the generated initial QR code image file can be 0.1*0.1-0.5*0.5mm. 2 It is relatively small in size;

[0036] Generate the inverse code of the QR code based on the QR code image file. The inverse code of the QR code should be larger than the initial QR code image file, for example, 1.1-1.3 times.

[0037] Adjusting the optical path of the laser marking system can make the focused spot of laser 1 smaller than the theoretical value;

[0038] Fill in the inverse code of the QR code to generate the actual processing drawing;

[0039] Adjust the laser focus of laser 1 to be located on the product surface;

[0040] Positioning the product surface is usually achieved by using a CCD camera to locate and calculate the processing position;

[0041] Laser 1 is used to laser mark the processing position on the product surface. Of course, before marking, the marking parameters of laser 1 should be adjusted so that a QR code image that meets the requirements can be marked.

[0042] In the above marking process, instead of directly using the generated initial QR code document for laser marking, the initial QR code document is first converted into a QR code inverse code. Of course, this conversion process can be completed in advance or corresponding conversion software can be set in the laser marking system to generate a processing document based on the QR code inverse code. Specifically, the QR code inverse code can be marked in the vector dotting mode, which can ensure the integrity of the QR code after marking to the greatest extent and also improve the marking efficiency. In addition, since the power required for the vector dotting mode is very small, there is almost no metal splash during the marking process, so the cleaning steps before and after marking can be omitted. Moreover, the marking method provided in this embodiment is very suitable for micro QR code marking. The laser 1 can use a nanosecond fiber laser 1, which reduces the cost compared with the commonly used picosecond laser 1.

[0043] Refining the above embodiment, when adjusting the focused spot of the laser 1, the theoretical value of the focused spot needs to be calculated first, which is related to the QR code size and the number of QR codes. Specifically, the theoretical value of the focused spot is d'. Then adjust the actual focused spot d of the laser 1 to be d < d'. For example, for a 0.2 * 0.2 mm 2 QR code with 17 - bit letters and numbers, the number of QR code bits is 17 * 17 bits, and the theoretical value d' is 11.7 um. For a 0.2 * 0.2 mm 2 QR code with 10 - bit letters and numbers, the number of QR code bits is 10 * 10 bits, and the theoretical value d' is 20 um. The actual focused spot of the laser 1 M 2 is the laser quality, f is the focal length of the focusing lens, λ is the wavelength of the incident light beam, D is the diameter of the incident light beam. Thus, the size of the actual focused spot can be determined by d < d', and then the corresponding configuration can be adjusted. In the preferred embodiment, the laser 1 uses a fiber laser 1, and the fiber laser 1 is a narrow - pulse - width laser 1 with a pulse - width range of 0.2 - 500 ns and a frequency range of 1 - 3000 khz. The exit spot of the laser 1 is 7 mm, and the M of the laser 1 2 < 1.2, the maximum single - pulse energy of the laser 1 is 1.0 mj, and an expander 3 is added to the external optical path of the laser 1. The expander 3 is selected as a 2X expander 3, the galvanometer 4 is a galvanometer 4 with a light - passing hole of 14 mm, and the focal length of the galvanometer 4 is 100 mm. The calculated focused spot d is 11 um. In the preferred solution of the laser 1, the pulse width is 2 - 8 ns, the frequency is 40 - 60 khz, the power is 0.3 - 0.5 W, the speed is 300 - 500 mm / s, the number of pulses per point is 3 - 4, and the dotting time is 0.1 - 0.3 ms.

[0044] In the optimized embodiment, the filling spacing of the QR code inversion is smaller than the focused spot of lens 5. This focused spot should be the actual focused spot under lens 5, ensuring seamless marking of the QR code after filling. Furthermore, the filling spacing of the QR code inversion and the theoretical value of the focused spot limit the range of values ​​for the actual focused spot.

[0045] See Figure 5 This invention also provides a laser marking machine, including a laser 1, a galvanometer 4, a lens 5, a worktable, a CCD camera 2, a ring light source 6, and a reflector 7. Light emitted from the laser 1 passes sequentially through the galvanometer 4 and lens 5 to the worktable. The lens 8 of the CCD camera 2 is directly opposite the ring aperture of the ring light source 6. Light emitted from the ring light source 6 is transmitted through the reflector 7 to the worktable, reflected by the worktable back to the reflector 7, and then reflected again by the reflector 7 to the camera. The laser marking machine provided in this embodiment corresponds to the above-described marking method, i.e., the laser marking machine operates using the above-described marking method. A beam expander 3 is placed in the optical path between the laser 1 and the galvanometer 4. The laser emitted from the laser 1 is magnified by the beam expander 3, then enters the galvanometer 4 for optical path deflection, is focused by the lens 5, and then reflected back by the reflector 7, resulting in vertical laser marking on the product. Ring light source 6 illuminates the product. Since the product is stainless steel, a blue ring light source 6 is selected. Lens 8 images the product surface, and CCD camera 2 generates image information, which is transmitted to a computer for image processing to generate product position information for positioning and marking. CCD camera 2 uses external coaxial vision, avoiding the use of a side-axis plus translation axis marking method to prevent product displacement during movement and affecting positioning and marking accuracy. Furthermore, when using laser processing, a suitable beam expansion factor is adopted based on the theoretical calculation formula of the laser 1's exit spot and focused spot, ensuring the focused spot is smaller than the theoretical value. Additionally, a reverse QR code is generated from the QR code image, and the reverse QR code is used to generate the processing image.

[0046] See Figures 5-7 The laser marking machine provided in this embodiment is highly suitable for marking small-sized QR codes. For these miniature QR codes, a nanosecond fiber laser is used, resulting in low marking costs. The marked miniature QR codes can be read by a camera, such as a 2000W camera with a 2X telecentric lens and a blue ring light. Furthermore, the laser marking machine requires very little power, and there is almost no metal spatter during the marking process, thus eliminating the need for a cleaning structure.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for laser marking a metal surface two-dimensional code, characterized in that, The method comprises the following steps: generating an initial two-dimensional code file, the initial two-dimensional code file has a size of 0.1*0.1-0.5*0.5mm 2 ; generating a two-dimensional code inverse code according to the two-dimensional code file, the two-dimensional code inverse code having a size of 1.1-1.3 times of the initial two-dimensional code file; The nanosecond laser is used, the power of the laser is 0.3-0.5W, the focused spot of the laser is less than a theoretical value, the filling interval of the two-dimensional code inverse code is less than the focused spot of the laser, and the theoretical value of the focused spot is d', The laser uses a fiber laser, the pulse width is 2-8ns, the frequency is 40-60KHz, the speed is 300-500mm / s, the number of pulses per point is 3-4, and the dotting time is 0.1-0.3ms. filling the two-dimensional code inverse code to generate a processing file, and the filling interval of the two-dimensional code inverse code is smaller than the focusing spot of the laser; adjusting the laser focus of the laser to be on the product surface; positioning the product surface and calculating the processing position; adopting the laser to perform laser marking on the processing position of the product surface.

2. The method of claim 1, wherein: The standard initial two-dimensional code file is generated by using a DATA MATRIX two-dimensional code coding mode.

3. The method of claim 1, wherein: The metal is stainless steel, and a blue ring-shaped light source is adopted to light the product surface during marking.

4. A laser marking machine comprising a laser, a galvanometer, a lens and a worktable, the laser emits light to the worktable through the galvanometer and the lens in turn, characterized in that: The device further comprises a camera, a ring-shaped light source, and an inclined mirror, the lens of the camera is directly opposite the ring hole of the ring-shaped light source, the ring-shaped light source emits light which is reflected to the workbench through the inclined mirror, and is reflected to the inclined mirror through the workbench, and the inclined mirror is reflected to the camera again, and the laser marking machine adopts the marking method according to any one of claims 1-3 to mark a two-dimensional code on the metal surface.

5. The laser marker of claim 4, wherein: The device further comprises an expander mirror, which is located on the light path between the laser and the galvanometer.

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