Laser marking method, device and storage medium for cylindrical workpieces

Abstract

The application discloses a laser marking method and device of a cylindrical workpiece and a storage medium, and belongs to the technical field of laser marking. The method comprises the following steps: acquiring a to-be-marked pattern and a radius parameter of the cylindrical workpiece; according to the radius parameter, the angular displacement of a rotating shaft is equivalent to a virtual straight-line moving shaft; a virtual plane coordinate system is constructed based on the virtual straight-line moving shaft and a scanning shaft of a galvanometer; the to-be-marked pattern is mapped into the virtual plane coordinate system; marking path instructions for controlling the galvanometer and the rotating shaft are generated; and according to the marking path instructions, the galvanometer is driven to perform linear scanning and the rotating shaft is driven to perform rotating movement, so that a laser beam etches the to-be-marked pattern on the surface of the cylindrical workpiece. Through the algorithm compensation mechanism of constructing the virtual plane coordinate system, the completeness and position accuracy of the marking pattern are ensured, so that the marking effect meeting the batch processing demand is achieved on a low-cost hardware platform.

Description

Technical Field

[0001] This application relates to the field of laser marking technology, and in particular to a laser marking method, equipment and storage medium for cylindrical workpieces. Background Technology

[0002] Two-dimensional graphic marking on the surface of cylindrical workpieces usually adopts a scheme of coordinated control of dual galvanometers and a rotating axis. That is, two galvanometers control the X-axis and Y-axis deflection of the laser beam respectively, and the rotating axis drives the workpiece to rotate, thereby forming a complete pattern on the cylindrical surface.

[0003] However, in actual processing scenarios, the dual-galvanometer laser marking process requires a high-precision galvanometer motor for each galvanometer, as well as its matching drive control system. This results in a high overall equipment cost for dual-galvanometer marking, making it difficult to implement.

[0004] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of this application is to provide a laser marking method, equipment and storage medium for cylindrical workpieces, aiming to solve the technical problem of high overall equipment cost required for dual-galvanometer marking of cylindrical workpieces.

[0006] To achieve the above objectives, this application provides a laser marking method for cylindrical workpieces, the method comprising the following steps: Obtain the graphic to be marked, as well as the radius parameters of the cylindrical workpiece; Based on the radius parameter, the angular displacement of the rotation axis is equivalent to a virtual linear motion axis, and a virtual planar coordinate system is constructed based on the virtual linear motion axis and the scanning axis of the galvanometer. The graphic to be marked is mapped onto the virtual plane coordinate system to generate marking path instructions for controlling the galvanometer and the rotation axis; According to the marking path instruction, the galvanometer is driven to perform linear scanning and the rotating axis is driven to rotate, so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece.

[0007] In one embodiment, the step of mapping the graphic to be marked onto the virtual plane coordinate system and generating marking path instructions for controlling the galvanometer and the rotation axis includes: Based on the radius parameter, the graphic to be marked is pre-distorted to obtain the corrected graphic data; The marking path instruction is generated based on the corrected graphic data.

[0008] In one embodiment, the step of performing pre-distortion correction on the graphic to be marked according to the radius parameter to obtain the corrected graphic data includes: In the virtual plane coordinate system, obtain the original coordinates of each point in the graphic to be marked; Based on the radius parameter, calculate the mapping relationship between the circumferential length and axial length of each point in the pattern to be marked on the surface of the cylindrical workpiece; Based on the mapping relationship, the axial coordinates of each point in the graphic to be marked are reversed to obtain the corrected graphic data.

[0009] In one embodiment, the step of mapping the graphic to be marked onto the virtual plane coordinate system and generating marking path instructions for controlling the galvanometer and the rotation axis includes: Path planning is performed on the graphic to be marked in the virtual plane coordinate system to generate a circumferential coordinate sequence containing a time series; Based on the circumferential coordinate sequence and the radius parameter, calculate the target angular displacement of the rotation axis at the target time, and calculate the deflection angle of the galvanometer at the target time; The marking path instruction is generated based on the target angular displacement and the deflection angle.

[0010] In one embodiment, the step of driving the galvanometer to perform linear scanning and the rotating axis to rotate according to the marking path instruction, so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece, includes: Obtain the preset scanning linear velocity of the galvanometer; The target angular velocity of the rotating axis is calculated based on the preset scan linear velocity and the radius parameter; During the marking process, the galvanometer is driven to move according to the preset scanning linear velocity, and the rotating shaft is driven to rotate synchronously according to the target angular velocity.

[0011] In one embodiment, the step of driving the galvanometer to perform linear scanning and the rotating axis to rotate according to the marking path instruction, so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece, further includes: Based on the circumferential irradiation position of the laser beam on the surface of the cylindrical workpiece and the radius parameter, the defocusing amount of the laser focus relative to the surface of the cylindrical workpiece is calculated; The position of the laser focus is adjusted according to the defocusing amount so that the laser focus is kept on the surface of the cylindrical workpiece.

[0012] In one embodiment, the step of adjusting the position of the laser focus according to the defocusing amount so that the laser focus is maintained on the surface of the cylindrical workpiece includes: Based on the defocusing amount, determine the target driving parameters of the liquid lens; By outputting a drive signal corresponding to the target drive parameters to the liquid lens, the radius of curvature of the liquid lens is adjusted so that after the laser focus moves by the defocusing amount along the optical axis, the laser focus falls on the surface of the cylindrical workpiece.

[0013] In one embodiment, after the step of calculating the defocusing amount of the laser focal point relative to the surface of the cylindrical workpiece based on the circumferential irradiation position of the laser beam on the surface of the cylindrical workpiece and the radius parameter, the method further includes: Calculate the target power output by the laser based on the defocusing amount; The laser is controlled to output the laser beam based on the target power.

[0014] In addition, to achieve the above objectives, this application also provides a laser marking device for cylindrical workpieces, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the laser marking method for cylindrical workpieces as described above.

[0015] In addition, to achieve the above objectives, this application also provides a storage medium, which is a computer-readable storage medium, and stores a computer program thereon. When the computer program is executed by a processor, it implements the steps of the laser marking method for cylindrical workpieces as described above.

[0016] One or more technical solutions proposed in this application have at least the following technical effects: This application obtains the radius parameters of the graphic to be marked and the cylindrical workpiece, and converts the angular displacement of the rotation axis into a virtual linear movement axis based on the radius parameters. A virtual planar coordinate system is then constructed with the scanning axis of the galvanometer. The graphic to be marked is then mapped into the virtual planar coordinate system to generate marking path instructions. Finally, the galvanometer is driven to perform linear scanning and the rotation axis to perform rotational motion according to the marking path instructions. Thus, two-dimensional graphic marking on the surface of a cylindrical workpiece is achieved with a hardware configuration of a single galvanometer and a rotation axis, reducing the hardware cost of the laser marking equipment. At the same time, while maintaining the coordination between the linear scanning of the galvanometer and the rotational motion of the rotation axis, the integrity and positional accuracy of the marked graphic are ensured through an algorithm compensation mechanism for constructing a virtual planar coordinate system. This achieves a marking effect that meets the needs of batch processing on a low-cost hardware platform. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the first embodiment of the laser marking method for cylindrical workpieces according to this application; Figure 2 This is a schematic diagram of the coordinate mapping relationship involved in the first embodiment of this application; Figure 3 This is a flowchart illustrating the second embodiment of the laser marking method for cylindrical workpieces according to this application; Figure 4 This is a schematic diagram of the structure of a laser marking device for cylindrical workpieces in the hardware operating environment of the embodiments of this application.

[0020] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0022] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0023] The main solution of this application embodiment is as follows: obtain the graphic to be marked and the radius parameters of the cylindrical workpiece; based on the radius parameters, the angular displacement of the rotation axis is equivalent to a virtual linear motion axis; a virtual plane coordinate system is constructed based on the virtual linear motion axis and the scanning axis of the galvanometer; the graphic to be marked is mapped into the virtual plane coordinate system; a marking path instruction for controlling the galvanometer and the rotation axis is generated; according to the marking path instruction, the galvanometer is driven to perform linear scanning and the rotation axis to perform rotational motion, so that the laser beam etches the graphic to be marked on the surface of the cylindrical workpiece.

[0024] Two-dimensional marking on the surface of cylindrical workpieces typically employs a dual-galvanometer and rotary axis coordinated control scheme. This involves two galvanometers controlling the X-axis and Y-axis deflection of the laser beam, respectively, while the rotary axis rotates the workpiece to form a complete pattern on the cylindrical surface. However, in practical processing scenarios, dual-galvanometer laser marking requires a high-precision galvanometer motor for each galvanometer, along with its corresponding drive control system. This results in a high overall equipment cost for dual-galvanometer marking, making its practical application difficult.

[0025] This application obtains the radius parameters of the graphic to be marked and the cylindrical workpiece, and converts the angular displacement of the rotation axis into a virtual linear movement axis based on the radius parameters. A virtual planar coordinate system is then constructed with the scanning axis of the galvanometer. The graphic to be marked is then mapped into the virtual planar coordinate system to generate marking path instructions. Finally, the galvanometer is driven to perform linear scanning and the rotation axis to perform rotational motion according to the marking path instructions. Thus, two-dimensional graphic marking on the surface of a cylindrical workpiece is achieved with a hardware configuration of a single galvanometer and a rotation axis, reducing the hardware cost of the laser marking equipment. At the same time, while maintaining the coordination between the linear scanning of the galvanometer and the rotational motion of the rotation axis, the integrity and positional accuracy of the marked graphic are ensured through an algorithm compensation mechanism for constructing a virtual planar coordinate system. This achieves a marking effect that meets the needs of batch processing on a low-cost hardware platform.

[0026] To better understand the above technical solutions, exemplary embodiments of this application will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0027] It should be noted that the executing entity in this embodiment can be the controller of a laser marking system, or a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device or laser marking device for cylindrical workpieces capable of the above functions. This embodiment does not specifically limit the specific implementation. The following description uses the controller of a laser marking system as an example to illustrate this embodiment and the subsequent embodiments.

[0028] Based on this, the embodiments of this application provide a laser marking method for cylindrical workpieces, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the laser marking method for cylindrical workpieces according to this application.

[0029] In this embodiment, the laser marking method for the cylindrical workpiece includes steps S10 to S40: Step S10: Obtain the graphic to be marked and the radius parameters of the cylindrical workpiece; In this embodiment, the controller is the central control unit of the laser marking system, which can be an embedded microprocessor, digital signal processor, or industrial computer, used to execute algorithm calculations and output control commands. The graphic data to be marked refers to the digital description of the two-dimensional pattern to be etched onto the surface of the cylindrical workpiece. This data is typically stored in vector graphics format and contains coordinate information for several lines, curves, or filled areas. The radius parameter refers to the outer surface radius of the cylindrical workpiece; this parameter is used to subsequently convert the planar coordinates into the actual arc length on the cylindrical surface.

[0030] Specifically, the controller first receives the graphic data to be marked from the host computer or input by the operator via a communication interface. This data can be in a standard vector format such as Drawing Exchange Format (DXF) or Plotter File (PLT). The controller parses the graphic data, extracting the geometric information of all elements, including the planar coordinates of each point, line segment connections, and the boundaries of the filled area. Simultaneously, the controller acquires the radius parameter of the cylindrical workpiece to be processed. This radius parameter can be manually entered into the control interface or automatically read from the feedback value of the distance sensor mounted on the rotating axis. The controller stores the acquired graphic data to be marked in a memory buffer and stores the radius parameter as a floating-point variable for subsequent steps.

[0031] Step S20: Based on the radius parameter, the angular displacement of the rotation axis is equivalent to a virtual linear translation axis, and a virtual planar coordinate system is constructed based on the virtual linear translation axis and the scanning axis of the galvanometer. It should be noted that, in order to replace redundant hardware with algorithms, the laser marking system constructs a "virtual Y-axis," that is, a virtual linear movement axis, to realize functions such as coordinate mapping, so as to support the system to perform real-time focus compensation and high-precision synchronous control.

[0032] In this embodiment, the angular displacement of the rotation axis refers to the angle value of the rotation axis rotating about its own axis from its initial position, usually expressed in radians or degrees. The virtual linear motion axis refers to converting the angular displacement of the rotation axis into an equivalent linear displacement according to the cylinder radius, thereby simulating a non-existent physical linear axis at the control algorithm level. The virtual planar coordinate system is a two-dimensional orthogonal coordinate system formed by using the scanning axis of the galvanometer as the horizontal axis and the virtual linear motion axis as the vertical axis. Each point in this coordinate system corresponds to a unique position on the surface of the cylindrical workpiece.

[0033] Specifically, the controller first establishes a mathematical transformation relationship between the angular displacement of the rotation axis and the circumferential arc length of the cylinder surface, i.e., the circumferential arc length equals the radius multiplied by the angular displacement. Based on this transformation relationship, the controller maps each angular displacement value of the rotation axis to a virtual linear displacement value, thus equating the rotation axis to a virtual linear movement axis moving along the cylinder axis. The controller then constructs a two-dimensional orthogonal virtual plane coordinate system with the galvanometer's scanning axis as the first coordinate axis and this virtual linear movement axis as the second coordinate axis. The origin of this coordinate system corresponds to the laser landing position when the galvanometer has zero deflection and the rotation axis has zero angular displacement. The controller allocates storage space for this coordinate system in memory and establishes a coordinate system transformation matrix, which is used to subsequently map the planar graphic coordinates into galvanometer deflection commands and rotation axis rotation commands.

[0034] In one implementation, the controller establishes a linear mapping function to map the angular displacement range of the rotation axis from 0 to 2π radians to the range of the virtual linear motion axis from 0 to 2πR, where R is a radius parameter. Then, it constructs an orthogonal coordinate system between the mapped virtual axis and the galvanometer scanning axis.

[0035] In another embodiment, the controller establishes a piecewise linear mapping, dividing the angular displacement of the rotation axis into segments at preset equal intervals, and mapping each segment using independent linear coefficients to adapt to imperfect cylindrical surfaces, i.e., cylindrical workpieces with slight tapers. Then, a virtual planar coordinate system is constructed based on the piecewise mapping results.

[0036] For example, the laser marking system is based on x=R·θ, which equates the integral of the angular displacement of the rotation axis (θ axis) to a virtual axial movement (Y axis), thereby forming an X-θ virtual plane coordinate system with the X axis of the galvanometer, where x is the circumferential length of the cylinder and θ is the angular displacement of the rotation axis, in radians (rad).

[0037] Step S30: Map the graphic to be marked onto the virtual plane coordinate system and generate marking path instructions for controlling the galvanometer and rotation axis; In this embodiment, the controller converts the coordinates of the graphic data to be marked in the original planar coordinate system into coordinates in the virtual planar coordinate system according to the definition rules of the virtual planar coordinate system, forming a marking path and corresponding marking path instructions. This ensures that the shape of the graphic in the virtual planar coordinate system correctly corresponds to the actual etching shape on the surface of the cylindrical workpiece. The marking path instructions are a series of control commands arranged in chronological order. Each command includes the target deflection angle of the galvanometer, the target angular displacement of the rotation axis, and the laser output control signal.

[0038] Specifically, the controller first reads the original planar coordinate points of the graphic data to be marked one by one. For each original coordinate point, according to the definition of the virtual planar coordinate system, the controller directly uses the x-coordinate of the point as the coordinate value of the galvanometer scanning axis, and maps the y-coordinate of the point to the coordinate value of the virtual linear motion axis through a pre-established transformation relationship, thus obtaining the new coordinate point of the point in the virtual planar coordinate system. The new coordinate points are arranged into a time sequence according to the marking order. For each coordinate point in the sequence, the controller calculates the angle that the galvanometer needs to deflect, which is equal to the arcsine of the coordinate point's x-coordinate divided by the galvanometer scanning focal length. Simultaneously, it calculates the angular displacement that the rotation axis needs to rotate, which is equal to the coordinate point's x-coordinate divided by the radius parameter. The calculated galvanometer deflection angle and rotation axis angular displacement are packaged into a marking path instruction and stored in the instruction buffer in chronological order. While generating the instruction, the execution timestamp of each instruction is calculated based on the distance between adjacent coordinate points and the preset marking speed to ensure accurate timing during subsequent drives.

[0039] In one embodiment, the controller performs pre-distortion correction on the graphic to be marked based on the radius parameter to obtain corrected graphic data, and generates marking path instructions based on the corrected graphic data.

[0040] Furthermore, the controller acquires the original coordinates of each point in the graphic to be marked in a virtual plane coordinate system. Based on the radius parameter, it calculates the mapping relationship between the circumferential length and axial length of each point in the graphic on the surface of the cylindrical workpiece. According to this mapping relationship, the axial coordinates of each point in the graphic to be marked are reverse-compensated to obtain the corrected graphic data.

[0041] Optionally, the controller performs path planning on the graphic to be marked in a virtual plane coordinate system, generating a circumferential coordinate sequence containing a time sequence. Based on the circumferential coordinate sequence and the radius parameter, it calculates the target angular displacement of the rotation axis at the target time and the deflection angle of the galvanometer at the target time. Based on the target angular displacement and deflection angle, it generates a marking path command. In the laser marking process of a cylindrical workpiece, the circumferential coordinate refers to the position measurement of a point on the surface of the cylindrical workpiece along the circumferential direction, i.e., the direction around the cylinder's axis. The circumferential coordinate sequence is a series of circumferential coordinate values ​​arranged in chronological order of the marking path, with each coordinate value corresponding to a target position of the laser beam on the circumferential direction of the cylinder surface. This sequence is usually expressed in units of length, representing the actual arc length traversed along the outer surface arc of the cylinder from a reference starting point. The circumferential length refers to the arc distance between any two points on the surface of the cylindrical workpiece along the circumferential direction.

[0042] For example, such as Figure 2 As shown, Figure 2This is a schematic diagram of the coordinate mapping relationship involved in this embodiment. The laser marking system performs reverse compensation on the coordinates of the input graphic to offset the distortion caused when mapped onto the cylinder. The correction formula is x'=x, y'=y·(1+x / (2πR)). Here, the circumferential coordinates remain essentially unchanged, while the axial coordinates undergo stretching compensation. After solving for the pre-distorted coordinates (x, y'), the system uses this set of corrected graphic coordinates to generate subsequent control commands. Thus, when the graphic is mapped onto the cylinder through a single-axis scan, it can be restored to the expected correct shape. This compensation formula is derived based on the geometric model of the cylinder's surface development and aims to pre-compensate for the axial stretching effect of the graphic caused by the cylinder's curvature.

[0043] Step S40: According to the marking path instruction, drive the galvanometer to perform linear scanning and the rotating axis to perform rotational motion so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece.

[0044] In this embodiment, the rotating shaft is used to drive the cylindrical workpiece to rotate around its own axis, and the galvanometer is used to change the direction of the laser beam emitted by the laser.

[0045] In one embodiment, the controller acquires the preset scanning linear velocity of the galvanometer and calculates the target angular velocity of the rotating shaft based on the preset scanning linear velocity and radius parameters. During the marking process, the controller drives the galvanometer to move according to the preset scanning linear velocity and synchronously drives the rotating shaft to move according to the target angular velocity.

[0046] Specifically, the controller reads the marking path instructions one by one from the instruction buffer. For each instruction, the controller first parses the target deflection angle of the galvanometer and the target angular displacement of the rotating shaft. The controller converts the target deflection angle of the galvanometer into an analog voltage signal or digital control word, outputs it to the galvanometer driver board via a digital-to-analog converter, and drives the galvanometer motor to deflect the reflector to the specified angle, thereby guiding the laser beam to the specified position in the circumferential direction of the cylindrical workpiece. Simultaneously, the controller converts the target angular displacement of the rotating shaft into a pulse train or bus instruction, outputs it to the servo driver of the rotating shaft, and drives the rotating shaft motor to rotate the cylindrical workpiece to the specified angular displacement. The controller synchronizes these two actions via a high-speed real-time bus to ensure that the rotating shaft has rotated into position when the laser beam reaches the workpiece surface. After both the galvanometer and the rotating shaft have reached the target position, the controller emits a laser emission signal, causing the laser to output a laser pulse to etch a point on the workpiece surface. The controller repeats the above process, etching all points sequentially according to the marking path instruction sequence, ultimately forming a complete predetermined pattern. Throughout the marking process, the controller continuously monitors the actual angular displacement fed back by the encoder and corrects the galvanometer instructions in real time to compensate for synchronization errors.

[0047] Optionally, during the marking process, the controller calculates and synchronously controls the movement of the galvanometer's X-axis and the rotation axis θ in real time based on the preprocessed graphic data. A linkage relationship is established between the X-axis galvanometer deflection angle α and the rotation axis angular displacement θ. By calculating θ(t) = x(t) / R, the rotation axis is controlled to rotate to a specified angle θ(t), and by calculating α(t) = arcsin(x(t) / f), the galvanometer is controlled to deflect to a specified angle to direct the laser to the circumferential position x(t). x(t) refers to the circumferential coordinate position that the galvanometer needs to scan at the current time t, which originates from the marking path planning of the preprocessed graphic in the previous step. Based on the preprocessed graphic data, the command values ​​of the galvanometer deflection angle α(t) and the rotation axis angular displacement θ(t) are calculated, and the movement of the two axes is controlled. At this time, the laser uses the original preset power P0 for marking.

[0048] Optionally, to ensure uniform marking, the galvanometer scanning linear velocity Vx needs to satisfy a strict relationship with the rotation axis angular velocity ω: Vx = R·ω. Microsecond-level synchronous control is achieved through a high-speed real-time bus, such as EtherCAT.

[0049] This embodiment of the application obtains the radius parameters of the graphic to be marked and the cylindrical workpiece. Based on the radius parameters, the angular displacement of the rotation axis is equivalent to a virtual linear movement axis, and a virtual planar coordinate system is constructed with the scanning axis of the galvanometer. The graphic to be marked is then mapped into the virtual planar coordinate system to generate a marking path instruction. Finally, the galvanometer is driven to perform linear scanning and the rotation axis to perform rotational motion according to the marking path instruction. Thus, two-dimensional graphic marking on the surface of the cylindrical workpiece is achieved with a hardware configuration of a single galvanometer and a rotation axis, reducing the hardware cost of the laser marking equipment. At the same time, while maintaining the coordination between the linear scanning of the galvanometer and the rotational motion of the rotation axis, the integrity and positional accuracy of the marked graphic are ensured by the algorithm compensation mechanism of constructing the virtual planar coordinate system. Thus, a marking effect that meets the batch processing requirements is achieved on a low-cost hardware platform.

[0050] Based on the same inventive concept, this application also provides a second embodiment, referring to... Figure 3 , Figure 3 This is a flowchart illustrating the second embodiment of the laser marking method for cylindrical workpieces according to this application.

[0051] In this embodiment, the laser marking method for the cylindrical workpiece further includes steps S41-S42: Step S41: Calculate the defocusing amount of the laser focus relative to the surface of the cylindrical workpiece based on the circumferential irradiation position and radius parameters of the laser beam on the surface of the cylindrical workpiece. Step S42: Adjust the laser focus position according to the defocusing amount so that the laser focus is kept on the surface of the cylindrical workpiece.

[0052] It should be noted that the laser marking system also needs to compensate for the defocusing effect caused by the curved surface of the cylinder in real time during marking. The defocusing effect refers to the phenomenon where the focal point of the laser beam deviates from the workpiece surface, resulting in an enlarged spot, decreased energy density, and poorer marking quality. In cylindrical laser marking, because the cylindrical surface is curved, the optical path length of the laser beam from the focusing lens to different circumferential positions varies with the illumination angle, causing the focal point to not always fall on the surface of the cylindrical workpiece, thus producing the defocusing effect. The defocus amount refers to the vertical distance between the actual focal point of the laser beam and the surface of the cylindrical workpiece. When the focal point falls exactly on the surface, the defocus amount is zero; when the focal point deviates from the surface, the defocus amount is a positive or negative value. The focal position refers to the spatial position where the energy of the laser beam is most concentrated after passing through the focusing lens.

[0053] In this embodiment, by real-time monitoring of the laser beam's irradiation position on the cylindrical curved surface, the focal deviation caused by the surface curvature is pre-calculated, and the focusing mechanism is actively adjusted to ensure the focal point always follows the workpiece surface. This overcomes the dynamic defocusing problem caused by the cylindrical curved surface in the single galvanometer plus rotating shaft solution. The circumferential irradiation position refers to the current position of the laser beam irradiating the cylindrical workpiece surface along the circumferential direction. This position is determined by the galvanometer's deflection angle or the rotating shaft's angular displacement, and is expressed in arc length units.

[0054] Specifically, the controller reads the circumferential irradiation position that the galvanometer needs to scan from the currently executed marking path instruction. Based on this circumferential irradiation position and the pre-stored cylindrical workpiece radius parameter, it calculates the defocus amount using surface geometry. Specifically, the central angle is obtained by dividing the circumferential irradiation position by the radius parameter. Then, the difference between multiplying the radius parameter by a factor subtracting the cosine of this central angle yields an approximate defocus amount. After obtaining the defocus amount, the controller determines if the absolute value of the defocus amount is positive and exceeds a preset depth-of-focus threshold, and then initiates focus adjustment. The controller outputs a drive signal to the focus adjustment device, causing the laser focus to move along the optical axis by the distance equal to the defocus amount, thereby refocusing the laser onto the surface of the cylindrical workpiece. The controller repeats the above calculation and adjustment process in each control cycle or at each marking point position, achieving real-time dynamic focus compensation.

[0055] For example, the controller calculates the focal offset Δz caused by the curved surface based on the circumferential position x(t) of the current laser beam irradiation point. Δz ≈ R·(1-cos(x(t) / R)), where a small angle approximation simplifies the calculation. A liquid lens is used to adjust the laser focal position in real time according to the calculated Δz, ensuring it always falls on the cylindrical surface. Simultaneously, the laser power is adjusted according to the defocusing amount to maintain a constant energy density on the workpiece surface. The formula is: P=P0·(d_dof / (d_dof+|Δz|)). P0 is the original laser power at the standard focal length. d_dof is the focal depth of the laser, such as 0.3mm. When the laser defocuses, the spot size increases, and the energy density decreases, resulting in lighter marking colors or failure to mark. The purpose of power compensation is to adjust the power accordingly when defocusing, maintaining a constant energy density and ensuring consistent marking results.

[0056] Optionally, the controller converts the defocusing amount into driving parameters for the focus adjustment device. For example, when using a mechanical focusing mechanism, the controller calculates the distance and direction the focusing lens needs to move. When using a liquid lens, the controller calculates the required driving current or voltage value for the liquid lens.

[0057] For example, the controller determines the target driving parameters of the liquid lens based on the defocusing amount, and adjusts the radius of curvature of the liquid lens by outputting the driving signal corresponding to the target driving parameters to the liquid lens so that the laser focus falls on the surface of the cylindrical workpiece after the laser focus moves the distance of the defocusing amount along the optical axis.

[0058] Optionally, since the laser spot area expands and the energy density per unit area decreases when defocusing, keeping the laser output power constant will result in shallower markings or even prevent effective etching. Therefore, it is necessary to adjust the laser output power in reverse according to the defocusing amount. The controller also calculates the target power of the laser output based on the defocusing amount and controls the laser beam output according to the target power.

[0059] Specifically, the controller first acquires the current defocus value of the laser beam. This value can be positive (focus above the workpiece surface) or negative (focus below the workpiece surface). Simultaneously, the controller acquires pre-stored laser depth-of-focus parameters and the original power parameters at the standard focal length. The controller calculates a power compensation coefficient based on the ratio of the absolute value of the defocus amount to the depth-of-focus parameter. Specifically, the controller divides the depth-of-focus parameter by the sum of the depth-of-focus parameter and the absolute value of the defocus amount to obtain the power compensation coefficient, which is less than or equal to one. The controller then divides the original power parameter by this power compensation coefficient to obtain the target power. When the defocus amount is zero, the compensation coefficient equals one, and the target power equals the original power; as the absolute value of the defocus amount increases, the compensation coefficient decreases, and the target power increases accordingly. The controller converts the calculated target power into an analog control voltage or digital control word for the laser and outputs it to the laser power supply through the control interface, causing the laser to output the laser beam at the target power. The controller performs the above calculations and adjustments before each laser emission point during the marking process to ensure that the energy density at each marking point remains constant.

[0060] Optionally, the controller also needs to detect and correct the synchronization error between the galvanometer and the rotating shaft in real time through sensor feedback. It corrects the drive from both the encoder and vision perspectives.

[0061] In one embodiment, a high-precision encoder is mounted on the rotating shaft to monitor its actual angular displacement θ_real in real time. θ_real is compared with the commanded angular displacement θ_cmd to calculate the angular error. This error is compensated by correcting the scanning position of the galvanometer: x_correct = x + R·(θ_real - θ_cmd). This formula corrects the circumferential coordinate command x(t) sent to the galvanometer. If the rotating shaft rotates too slowly (θ_real < θ_cmd), the galvanometer scanning speed is reduced (x_correct > x) to wait for the rotating shaft, thereby eliminating pattern misalignment.

[0062] In another embodiment, the controller also employs visual correction. The positions of the marked pattern feature points are detected in real time using a linear charge-coupled device (CCD) camera. Deviation detection compares the detected actual marking position with the pre-stored theoretical position to determine the position deviation. A proportional-integral-derivative (PID) controller is then used to dynamically adjust the angular velocity command of the rotation axis based on this position deviation: ω_adj = ω_0 + (Kp·e + Ki·∫edt + Kd·de / dt). Here, ω_0 is the planned angular velocity, e is the position deviation, and Kp, Ki, and Kd are the PID control parameters.

[0063] Since the system described in Embodiment 2 of this application is a system used to implement the method of Embodiment 1 of this application, those skilled in the art can understand the specific structure and variations of the system based on the method described in Embodiment 1 of this application, and therefore will not be described again here. All systems used in the method of Embodiment 1 of this application fall within the scope of protection of this application.

[0064] This application provides a laser marking device for cylindrical workpieces, the device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the laser marking method for cylindrical workpieces described in Embodiment 1 above.

[0065] The following is for reference. Figure 4 The diagram illustrates a structural schematic of a laser marking device suitable for implementing the embodiments of this application for cylindrical workpieces. The laser marking device for cylindrical workpieces in the embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 4 The laser marking equipment for cylindrical workpieces shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0066] like Figure 4As shown, the laser marking equipment for cylindrical workpieces may include a processing unit 1001 (e.g., a core processor, graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the laser marking equipment for cylindrical workpieces. The processing unit 1001, the read-only memory 1002, and the RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the laser marking equipment for cylindrical workpieces to exchange data wirelessly or via wired communication with other devices. Although laser marking equipment for cylindrical workpieces with various systems is shown in the figures, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems can be implemented alternatively.

[0067] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from read-only memory 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0068] The laser marking equipment for cylindrical workpieces provided in this application, employing the laser marking method for cylindrical workpieces described in the above embodiments, can solve the technical problem of high overall equipment cost required for dual-galvanometer marking of cylindrical workpieces. Compared with the prior art, the beneficial effects of the laser marking equipment for cylindrical workpieces provided in this application are the same as those of the laser marking method for cylindrical workpieces provided in the above embodiments, and other technical features of this laser marking equipment for cylindrical workpieces are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0069] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0070] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0071] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the laser marking method for cylindrical workpieces in the above embodiments.

[0072] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, radio frequency (RF), etc., or any suitable combination thereof.

[0073] The aforementioned computer-readable storage medium may be included in the laser marking equipment for cylindrical workpieces; or it may exist independently and not be assembled into the laser marking equipment for cylindrical workpieces.

[0074] The aforementioned computer-readable storage medium carries one or more programs. When the aforementioned one or more programs are executed by the laser marking device for the cylindrical workpiece, the laser marking device for the cylindrical workpiece causes the following: it acquires the graphic to be marked and the radius parameters of the cylindrical workpiece; based on the radius parameters, it equates the angular displacement of the rotation axis to a virtual linear motion axis; it constructs a virtual plane coordinate system based on the virtual linear motion axis and the scanning axis of the galvanometer; it maps the graphic to be marked onto the virtual plane coordinate system; it generates marking path instructions for controlling the galvanometer and the rotation axis; and based on the marking path instructions, it drives the galvanometer to perform linear scanning and the rotation axis to perform rotational motion, so that the laser beam etches the graphic to be marked on the surface of the cylindrical workpiece.

[0075] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0076] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0077] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0078] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the laser marking method for cylindrical workpieces described above. This solves the technical problem of high overall equipment costs required for dual-galvanometer marking of cylindrical workpieces. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the laser marking method for cylindrical workpieces provided in the above embodiments, and will not be repeated here.

[0079] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A laser marking method for cylindrical workpieces, characterized in that, The method includes the following steps: Obtain the graphic to be marked, as well as the radius parameters of the cylindrical workpiece; Based on the radius parameter, the angular displacement of the rotation axis is equivalent to a virtual linear motion axis, and a virtual planar coordinate system is constructed based on the virtual linear motion axis and the scanning axis of the galvanometer. The graphic to be marked is mapped onto the virtual plane coordinate system to generate marking path instructions for controlling the galvanometer and the rotation axis; According to the marking path instruction, the galvanometer is driven to perform linear scanning and the rotating axis is driven to rotate, so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece. The step of mapping the graphic to be marked onto the virtual plane coordinate system and generating marking path instructions for controlling the galvanometer and the rotation axis includes: performing path planning on the graphic to be marked in the virtual plane coordinate system to generate a circumferential coordinate sequence containing a time series; calculating the target angular displacement of the rotation axis at the target time based on the circumferential coordinate sequence and the radius parameter, and calculating the deflection angle of the galvanometer at the target time; and generating the marking path instructions based on the target angular displacement and the deflection angle.

2. The laser marking method for cylindrical workpieces as described in claim 1, characterized in that, The step of mapping the graphic to be marked onto the virtual plane coordinate system and generating marking path instructions for controlling the galvanometer and the rotation axis includes: Based on the radius parameter, the graphic to be marked is pre-distorted to obtain the corrected graphic data; The marking path instruction is generated based on the corrected graphic data.

3. The laser marking method for cylindrical workpieces as described in claim 2, characterized in that, The step of performing pre-distortion correction on the graphic to be marked based on the radius parameter to obtain the corrected graphic data includes: In the virtual plane coordinate system, obtain the original coordinates of each point in the graphic to be marked; Based on the radius parameter, calculate the mapping relationship between the circumferential length and axial length of each point in the pattern to be marked on the surface of the cylindrical workpiece; Based on the mapping relationship, the axial coordinates of each point in the graphic to be marked are reversed to obtain the corrected graphic data.

4. The laser marking method for cylindrical workpieces as described in claim 1, characterized in that, The step of driving the galvanometer to perform linear scanning and the rotating axis to rotate according to the marking path instruction, so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece, includes: Obtain the preset scanning linear velocity of the galvanometer; The target angular velocity of the rotating axis is calculated based on the preset scan linear velocity and the radius parameter; During the marking process, the galvanometer is driven to move according to the preset scanning linear velocity, and the rotating shaft is driven to rotate synchronously according to the target angular velocity.

5. The laser marking method for cylindrical workpieces as described in claim 1, characterized in that, The step of driving the galvanometer to perform linear scanning and the rotating axis to rotate according to the marking path instruction, so that the laser beam etches the pattern to be marked on the surface of the cylindrical workpiece, further includes: Based on the circumferential irradiation position of the laser beam on the surface of the cylindrical workpiece and the radius parameter, the defocusing amount of the laser focus relative to the surface of the cylindrical workpiece is calculated; The position of the laser focus is adjusted according to the defocusing amount so that the laser focus is kept on the surface of the cylindrical workpiece.

6. The laser marking method for cylindrical workpieces as described in claim 5, characterized in that, The step of adjusting the position of the laser focus according to the defocusing amount so that the laser focus is maintained on the surface of the cylindrical workpiece includes: Based on the defocusing amount, determine the target driving parameters of the liquid lens; By outputting a drive signal corresponding to the target drive parameters to the liquid lens, the radius of curvature of the liquid lens is adjusted so that after the laser focus moves by the defocusing amount along the optical axis, the laser focus falls on the surface of the cylindrical workpiece.

7. The laser marking method for cylindrical workpieces as described in claim 5, characterized in that, After the step of calculating the defocusing amount of the laser focal point relative to the surface of the cylindrical workpiece based on the circumferential irradiation position of the laser beam on the surface of the cylindrical workpiece and the radius parameter, the method further includes: Calculate the target power output by the laser based on the defocusing amount; The laser is controlled to output the laser beam based on the target power.

8. A laser marking device for cylindrical workpieces, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the laser marking method for a cylindrical workpiece as described in any one of claims 1 to 7.

9. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the laser marking method for a cylindrical workpiece as described in any one of claims 1 to 7.

Images