Real-time automatic focusing linear laser cleaning head

Abstract

The utility model relates to a kind of line laser cleaning head of real-time automatic focusing.The line laser cleaning head includes control unit, protective shell and focus unit being arranged in the inside of protective shell;The front side wall of the protective shell is provided with window mirror, and bottom is provided with bottom light hole;The upper, lower, left, right four side surfaces of protective shell are respectively provided with Z+ distance measuring module, Z-distance measuring module, X-distance measuring module, X+ distance measuring module;The focus unit includes linear displacement module and 45 ° reflector frame;Linear displacement module is slidably provided with focusing mirror frame, and focusing mirror frame and 45 ° reflector frame are respectively provided with cylindrical focusing mirror and 45 ° reflector.The utility model separates the design of laser ranging point and laser cleaning point, avoids the influence of the flash generated in cleaning process on ranging signal;Meanwhile, laser ranging point and laser cleaning point are at a certain distance, which can make focusing module get sufficient reaction time, enhance the real-time of focusing process.

Description

Technical Field

[0001] This utility model specifically relates to a real-time automatic focusing line laser cleaning head, belonging to the technical field of laser cleaning. Background Technology

[0002] With the continuous advancement of the national strategies of "Industry 4.0" and "Made in China 2025," and the new requirements for green development put forward by the goals of "peak carbon dioxide emissions and carbon neutrality" for the manufacturing industry, laser cleaning technology has become a key application area in my country's advanced manufacturing field. Compared with various traditional physical or chemical cleaning methods, laser cleaning has the characteristics of being non-contact, consumable-free, pollution-free, high-precision, and causing little or no damage, which is in line with the concepts of green environmental protection and intelligentization.

[0003] Based on the mechanism of interaction between the laser beam and the material, laser cleaning mainly relies on the focusing lens of the cleaning head to focus the laser beam onto the surface of the object to be cleaned. The high energy density focused spot causes the surface contaminants to be instantly heated, vaporized, or peeled off, thus achieving the cleaning of the material surface. Therefore, the relative position of the laser focus and the surface of the workpiece directly affects the quality of laser cleaning.

[0004] Currently, large-area laser cleaning typically involves focusing a high-energy laser beam into a line spot using a cylindrical lens. The relative distance between the cleaning head and the workpiece surface is fixed, and the line spot moves along its vertical direction to achieve high-efficiency cleaning. However, for workpieces with uneven surfaces and height differences, the focal point needs to be continuously adjusted to ensure it is focused on the workpiece surface. Traditional focusing methods for standard workpieces involve importing the workpiece's surface model into the laser cleaning control program and using algorithms to calculate the alignment of the focal point with the processing surface in the laser cleaning path. For non-standard, model-less workpieces with free-form surfaces, the relative distance between the cleaning head and the processing surface needs to be detected, and the focal point position continuously adjusted. Distance detection methods typically include high-response, high-precision laser ranging or ultrasonic ranging.

[0005] Because the returned light from laser ranging is interfered with by the dazzling white light generated during laser cleaning, and ultrasonic ranging is interfered with by the sharp noise during laser cleaning, data fluctuations occur. In addition, the electronically controlled displacement stage or cleaning head load platform used for focusing often has a certain delay, so it is impossible to measure the distance and accurately focus on the cleaning point in real time during laser cleaning. It is necessary to turn off the high-energy laser pre-path before laser cleaning, record the height difference changes in the cleaning path, and adjust the focus during the actual cleaning process, which seriously reduces the cleaning efficiency.

[0006] How to perform real-time laser ranging and focusing is an urgent problem to be solved in order to achieve intelligent, high-efficiency, and large-scale curved surface cleaning processes in laser cleaning equipment. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention provides a real-time autofocus line laser cleaning head.

[0008] The technical solution of this utility model is as follows:

[0009] A real-time autofocus line laser cleaning head includes a control unit, a protective housing, and a focusing unit disposed inside the protective housing.

[0010] The protective shell has a window mirror on its front side wall and a bottom light-transmitting hole at its bottom; the top, bottom, left, and right sides of the protective shell are respectively equipped with a Z+ ranging module, a Z- ranging module, an X- ranging module, and an X+ ranging module.

[0011] The focusing unit includes a linear displacement module and a 45° reflecting mirror mount; a focusing mirror mount is slidably mounted on the linear displacement module, and a cylindrical focusing mirror and a 45° reflecting mirror are respectively mounted on the focusing mirror mount and the 45° reflecting mirror mount.

[0012] The control unit is communicatively connected to both the ranging module and the linear displacement module.

[0013] Preferably, the ranging module on the side of the protective shell is a laser ranging module with a repeatability accuracy of over ±500μm.

[0014] Preferably, the linear displacement module uses a magnetic axis displacement platform with a stroke greater than 100mm. The magnetic axis displacement platform can achieve high acceleration and movement speed.

[0015] Preferably, the 45° reflector is coated with a high damage threshold and high reflectivity film on one side, and the cylindrical focusing lens and the window lens are coated with a high damage threshold and high transmittance film on both sides. The focal length of the cylindrical focusing lens is greater than M, where M is the distance between the cylindrical focusing lens and the window lens when the cylindrical focusing lens is closest to the 45° reflector frame.

[0016] Preferably, the detection laser beam emitted by the ranging module is parallel to the line laser beam emitted from the hair washing area. Within the same XZ plane, the centers of the four detection laser spots and the working laser spot are arranged in a right cross shape, without overlapping each other, and the distance between each ranging module and the center of the working laser spot is equal; effectively avoiding mutual interference between the detection laser and the working laser.

[0017] The beneficial effects of this utility model are as follows:

[0018] 1. This utility model utilizes four laser ranging modules to achieve laser ranging in different laser cleaning directions;

[0019] 2. This utility model separates the laser ranging point and the laser cleaning point to avoid the influence of the flash generated during the cleaning process on the ranging signal; at the same time, the distance between the laser ranging point and the laser cleaning point allows the focusing module sufficient reaction time, enhancing the real-time performance of the focusing process.

[0020] 3. This utility model eliminates the need for surface model import and path pre-scanning; it solves the problem of pre-identifying the scanning path and focusing distance required for laser cleaning of irregular curved surfaces, effectively improving laser cleaning efficiency.

[0021] 4. The line laser cleaning head described in this utility model has a simple optical path and strong stability, making it suitable for integrated production and industrial applications. Attached Figure Description

[0022] Figure 1 This is an overall schematic diagram of the real-time automatic focusing line laser cleaning head of this utility model.

[0023] Figure 2 This is an internal schematic diagram of the real-time automatic focusing line laser cleaning head of this utility model.

[0024] Figure 3 This is a schematic diagram of the 45° reflector frame described in this utility model;

[0025] Figure 4 This is a schematic diagram of the focusing frame described in this utility model;

[0026] Figure 5 This is a schematic diagram of the bow-shaped scanning path and the orientation of the ranging point described in this utility model;

[0027] Figure 6 This is a schematic diagram of the control method described in this invention;

[0028] Figure 7 This is a flowchart of the automatic focusing process of the line laser cleaning head described in this utility model;

[0029] In the diagram: 1-1, Z+ ranging module; 1-2, X+ ranging module; 1-3, Z- ranging module; 1-4, X- ranging module; 2-1, 45° reflecting mirror; 2-2, cylindrical focusing mirror; 2-3, window mirror; 2-4, bottom light passage; 3-1, 45° reflecting mirror frame; 3-2, focusing mirror frame; 3-3, window plate; 3-4, linear displacement module; 4-1, top plate; 4-2, rear plate; 4-3, first side plate; 4-4, bottom plate; 4-5, second side plate. Detailed Implementation

[0030] The following describes some embodiments of the present invention in detail with reference to the accompanying drawings.

[0031] Example 1

[0032] As Figure 1-4 shown

[0033] A line laser cleaning head with real-time automatic focusing includes a control unit, a protective housing, and a focusing unit arranged inside the protective housing; a window mirror 2-3 is provided on the front side wall of the protective housing, and a bottom light passing hole 2-4 is provided at the bottom; Z+ ranging modules 1-1, Z- ranging modules 1-3, X- ranging modules 1-4, and X+ ranging modules 1-2 are respectively arranged on the upper, lower, left, and right side surfaces of the protective housing; the focusing unit includes a linear displacement module 3-4 and a 45° mirror holder 3-1; a focusing lens holder 3-2 is slidably arranged on the linear displacement module 3-4, and a cylindrical focusing lens 2-2 and a 45° mirror 2-1 are respectively arranged on the focusing lens holder 3-2 and the 45° mirror holder 3-1; the control unit is respectively communicatively connected with the ranging module and the linear displacement module 3-4. In this embodiment, the control unit is a PLC control module.

[0034] In this embodiment, the protective housing is surrounded by a window plate 3-3, a top plate 4-1, a bottom plate 4-4, a rear plate 4-2, a first side plate 4-3, and a second side plate 4-5; a circular groove is formed on the front surface of the window plate 3-3, and threads are formed on the inner wall of the circular groove. The circular groove is used to place the window mirror 2-3, and the threads are used to cooperate with the window mirror gland for limiting; through holes are formed in the front and rear parts of the top plate 4-1, and are respectively threadedly connected to the upper surfaces of the window plate 3-3 and the rear plate 4-2. Through holes are formed in the front and rear parts of the bottom plate 4-4, and are respectively threadedly connected to the lower surfaces of the window plate 3-3 and the rear plate 4-2. Threaded holes are provided on the left and right surfaces of the window plate 3-3 and the rear plate 4-2, and are connected to the first side plate 4-3 and the second side plate 4-5;

[0035] Threaded holes are formed on the outer surfaces of the top plate 4-1, the bottom plate 4-4, the first side plate 4-3, and the second side plate 4-5 for fixing the ranging module; a threaded hole is formed on the front upper surface of the bottom plate 4-4 for fixing the linear displacement module 3-4; threaded holes are formed on both sides of the bottom light passing hole 2-4 at the rear of the bottom plate 4-4 for fixing the 45° mirror holder 3-1.

[0036] The 45° mirror holder 3-1 is of an inclined platform structure, with a light channel formed inside, a circular groove formed on the inclined surface, and threads formed on the inner side of the circular groove. The circular groove is used to place the 45° mirror 2-1, and the threads are used to cooperate with the mirror gland for limiting.

[0037] The focusing lens holder 3-2 is of a "mouth" - shaped structure, and the upper cross beam is for threaded connection to fix the cylindrical focusing lens 2-2. A boss is provided on the upper surface of the lower part to limit the displacement of the cylindrical focusing lens 2-2.

[0038] As Figure 6 、 Figure 7 shown, the working method of the line laser cleaning head in this embodiment includes the following steps:

[0039] 1) Mount the line laser cleaning head onto an external moving platform that drives its movement; and connect the external moving platform to the control unit;

[0040] 2) A square laser beam is input through the bottom light-transmitting hole 2-4. The laser beam is deflected 90° by the 45° reflector 2-1. The parallel-transmitted square laser beam becomes a line laser beam after passing through the cylindrical focusing lens 2-2, and then is output through the window lens 2-3.

[0041] 3) Start the external moving platform to drive the cleaning head to perform cleaning motion in the XZ plane. The control unit judges the X+, X-, Z+, and Z- direction signals of the line laser cleaning head in the bow-shaped motion in real time. When moving in one of the directions, the distance signal measured by the ranging module in this direction is sent to the control unit. In actual operation, the laser cleaning motion is a bow-shaped reciprocating scanning motion.

[0042] 4) The control unit calculates the distance S that the cylindrical focusing lens 2-2 needs to move and the cylindrical focusing lens delay t:

[0043] t = L / V;

[0044] In the XZ plane, four ranging points are arranged in a "right cross" around the focal point, with the focal point at the center of the "right cross". The distance between the focal point and each of the four ranging points is L. At any given moment, the distance measured by the ranging module is not the distance that the focal point needs to be aligned with. When the cleaning head moves toward a certain ranging point at a speed V, the linear displacement module adjusts the position of the cylindrical focusing lens according to the distance measured by that ranging point at the previous moment. This is equivalent to the distance signal from the ranging module being fed back to the linear displacement module after a delay of t. This process is continuous; that is, after a delay of t, the center of the ranging point corresponds to the center of the focal point in real time.

[0045] The displacement of the cylindrical focusing lens is S = Dd;

[0046] Where D: the distance between the ranging module and the target workpiece; the cleaning head has four directions of movement: up, down, left, and right, and the four ranging modules are distributed in these four directions. The ranging signal of the direction in which the cleaning head moves is selected.

[0047] d: Minimum distance between the focal point and the cleaning head; The focal point is the point where the cylindrical focusing lens 2-2 focuses the square light spot into a line light spot. When the cylindrical focusing lens 2-2 is closest to the 45° reflecting mirror frame 3-1, the distance between the focal point and the cleaning head is at its minimum.

[0048] L: The distance between the focal point and the ranging point in the XZ plane; The laser ranging module itself has a transmitting window and a receiving window. When measuring distance, the transmitting window will emit a laser beam. This laser beam hits the surface of the workpiece and presents a dot-shaped light spot (i.e., the ranging point). At this time, the receiving window will identify the position between this dot-shaped light spot and the ranging module to complete the distance measurement.

[0049] V: Real-time movement speed of the cleaning head;

[0050] 5) After a delay time t, the control unit sends the distance S that the cylindrical focusing lens needs to move to the linear displacement module.

[0051] 6) After receiving the instruction, the linear displacement module controls the cylindrical focusing lens to adjust its position in real time, and completes real-time focusing so that the focus of the working laser is always located on the workpiece surface.

[0052] 7) Repeat steps 3)-6) to complete the cleaning of the workpiece surface. For example... Figure 5 As shown, laser cleaning is achieved by the cleaning head moving along a specific path. This path needs to be defined according to the processing scenario. For example, when the cleaning head moves to the right in a bow-shaped motion, it generates a →↓→↑ movement direction. This movement direction determines the selection of the ranging module; the ranging signal measured by the ranging module in the direction of movement is selected. When the cleaning head moves to the right in a bow-shaped motion, moving to → selects the ranging module on the right; moving to ↓ immediately switches to the ranging module below; moving to → again switches back to the ranging module on the right, and so on.

[0053] In this embodiment, the external moving platform is a multi-joint robotic arm or an electrically controlled linear displacement module; the external moving platform has a stroke greater than 1.5 × 1.5 m and a speed adjustable within the range of 20 mm / s to 400 mm / s. The external moving platform can drive the cleaning head to move within the same plane.

[0054] When the displacement of the cylindrical focusing lens is less than 0 or greater than the maximum stroke, the control unit will sound an alarm and stop the cleaning process.

[0055] Example 2

[0056] As described in Example 1, the real-time autofocus line laser cleaning head further includes a laser ranging module on the side of the protective shell, with a repeatability accuracy higher than ±500μm.

[0057] Example 3

[0058] As described in Example 1, the real-time autofocus line laser cleaning head further utilizes a magnetic axis displacement platform with a stroke greater than 100mm for the linear displacement module 3-4.

[0059] Example 4

[0060] As described in Example 1, the real-time autofocus line laser cleaning head further includes a 45° reflector 2-1 with a high damage threshold and high reflectivity film on one side, and a cylindrical focusing lens 2-2 and a window lens 2-3 with a high damage threshold and high transmittance film on both sides. The focal length of the cylindrical focusing lens 2-2 is greater than M, where M is the distance between the cylindrical focusing lens 2-2 and the window lens 2-3 when the cylindrical focusing lens 2-2 is closest to the 45° reflector frame 3-1.

[0061] Example 5

[0062] As described in Example 1, in the real-time autofocus line laser cleaning head, the detection laser beam emitted by the ranging module is parallel to the line laser beam emitted by the cleaning head.

Claims

1. A real-time autofocusing line laser cleaning head, characterized in that, The system includes a control unit, a protective housing, and a focusing unit housed inside the protective housing. The front wall of the protective housing has a window mirror, and the bottom has a bottom light-transmitting hole. The top, bottom, left, and right sides of the protective housing are respectively equipped with a Z+ ranging module, a Z- ranging module, an X- ranging module, and an X+ ranging module. The focusing unit includes a linear displacement module and a 45° reflecting mirror mount. A focusing mirror mount is slidably mounted on the linear displacement module, and a cylindrical focusing lens and a 45° reflecting mirror are respectively mounted on the focusing mirror mount and the 45° reflecting mirror mount. The control unit is communicatively connected to both the ranging module and the linear displacement module.

2. The real-time autofocusing line laser cleaning head according to claim 1, characterized in that, The ranging module on the side of the protective shell is a laser ranging module, with a repeatability accuracy of over ±500μm.

3. The real-time autofocusing line laser cleaning head according to claim 1, characterized in that, The linear displacement module uses a magnetic shaft displacement platform with a stroke greater than 100mm.

4. The real-time autofocusing line laser cleaning head according to claim 1, characterized in that, The 45° reflecting mirror is coated with a high damage threshold and high reflectivity film on one side, while the cylindrical focusing mirror and the window mirror are coated with a high damage threshold and high transmittance film on both sides. The focal length of the cylindrical focusing mirror is greater than M, where M is the distance between the cylindrical focusing mirror and the window mirror when the cylindrical focusing mirror is closest to the 45° reflecting mirror frame.

5. The real-time autofocusing line laser cleaning head according to claim 1, characterized in that, Make the detection laser beam emitted by the ranging module parallel to the linear laser beam emitted by the hair washing process.

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