Four-axis galvanometer laser processing device

Abstract

The invention provides a four-axis galvanometer laser processing device, which belongs to the technical field of laser precision processing and galvanometer scanning control, and comprises a laser, a three-axis galvanometer scanning module and a rotary light path module, the three-axis galvanometer scanning module comprises a first galvanometer, a second galvanometer and a dynamic focusing unit. The first galvanometer and the second galvanometer are used for controlling light beams to deflect in the X-axis direction and the Y-axis direction. The rotating light path module is arranged on an emergent light path of the three-axis galvanometer scanning module and comprises a hollow motor, a hollow motor rotor frame, a first reflecting mirror and a second reflecting mirror, and the first reflecting mirror and the second reflecting mirror are sequentially arranged along the light path and are obliquely arranged relative to the rotating axis of the hollow motor. And the hollow motor is used for driving the first reflecting mirror and the second reflecting mirror to rotate integrally, so that the emitted laser beam performs 360-degree rotary scanning around the rotating axis of the hollow motor. Oblique incidence scanning removal of laser on the side wall of the blind hole is achieved, a system light path is more concise, the number of needed precise elements is small, and the manufacturing and maintenance cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of laser precision machining and galvanometer scanning control technology, and more specifically, relates to a four-axis galvanometer laser machining device. Background Technology

[0002] Traditional biaxial galvanometer scanning heads achieve high-speed in-plane scanning through two oscillating X and Y mirrors, widely used in marking, engraving, welding, and micromachining. To expand the processing range and adapt to the machining of three-dimensional curved surfaces or deep cavities, the industry has developed a "3D dynamic focusing scanning system" that adds a Z-axis dynamic focusing module to the X and Y galvanometers. This system compensates for the height of the object surface by shifting the focal length, achieving precise focusing over a larger range. Existing triaxial dynamic focusing heads typically employ the following 3D scanning head structure: a set of zoom or scanning lenses that move with the Z-axis is added behind the X / Y galvanometers to achieve dynamic adjustment of the working distance and focal position.

[0003] Currently, in industries such as electronics and semiconductors, there is a need to remove the silver plating layer deposited on the inner wall of blind holes. However, due to the unique structure of blind holes, traditional vertical laser incidence methods are difficult to effectively irradiate the silver plating layer on the sidewalls of blind holes, resulting in poor removal efficiency and effectiveness. To address the problem of laser energy being difficult to apply to the sidewalls of blind holes, various oblique laser incidence processing solutions have been proposed in the industry.

[0004] A common approach is a laser beam rotating galvanometer system, such as the combination of beam rotation and focusing method with galvanometer scanning disclosed in Chinese patent CN101856772A. This approach uses a beam rotator (e.g., a rotating wedge prism, off-axis rotating lens, etc.) mounted on a hollow shaft high-speed motor, causing the laser beam to rotate around the axis before being deflected and focused by the galvanometer, achieving a process similar to "spiral drilling." This approach enables the laser to cut along a spiral trajectory, thereby increasing the machined hole diameter and facilitating slag removal.

[0005] Another existing approach uses an optical wedge / image rotator to achieve oblique incidence and rotation of the beam. For example, US Patent 7842901B2 proposes changing the tilt angle of the output beam by rotating an adjustable-angle optical wedge to control the aperture roundness. In this approach, the optical wedge not only needs to rotate at a constant speed around its central axis, but also needs to perform pitch motion to change the incident angle, which is a composite motion control.

[0006] In addition, commercially available five-axis laser scanning systems (such as Scanlab's precSYS) utilize X / Y dual-axis galvanometers combined with two tilt adjustment axes and a dynamic focusing axis to achieve precise machining of laser beams at arbitrary tilt angles in space. These systems can perform high-precision laser tilt-incident micromachining, capable of fabricating complex micro-hole structures such as cylinders and positive / negative cones.

[0007] However, all of the above-mentioned existing technical solutions have obvious shortcomings: (1) Complex structure and high cost: The beam rotation system using image rotators such as Dove prisms requires high-precision hollow shaft motors and precision optical components, resulting in a large system size and high price. The five-axis scanning head integrates multi-axis drive and control unit, which also leads to high equipment cost and strict maintenance requirements.

[0008] (2) High difficulty in alignment and control: Using schemes such as the rotating wedge prism requires achieving high-speed rotation and pitch composite motion of the optical wedge, which involves complex control algorithms and easy accumulation of errors. When using the Dove prism for rotation, it is also necessary to accurately calibrate its angle and optical axis and synchronize the galvanometer scanning, which increases the difficulty of system debugging. The calibration process of the five-axis linkage system is complex, requiring precise alignment of the laser focus and the coordinates of each axis, and the workload of initial alignment and subsequent calibration is large.

[0009] (3) Limited efficiency and applicability: Some solutions achieve large-area processing through a two-dimensional motion platform, but the mechanical movement speed is slow and acceleration and deceleration take a long time. Conventional vertical incidence galvanometers are ineffective for blind holes with large depth-to-diameter ratios, making it difficult to remove sidewall melts in a timely manner. Among the existing oblique incidence solutions, many can only provide relatively small tilt angles (such as ±7.5°), which have limited effectiveness in removing silver layers from the sidewalls of blind holes that require larger tilt angles.

[0010] In summary, existing technologies struggle to balance a sufficiently large oblique incidence angle with a simple and low-cost system. Therefore, it is necessary to provide a new technical solution that achieves omnidirectional oblique incidence of laser light on the inner wall of blind holes with a simpler and more intuitive structure, thereby improving the efficiency and quality of silver plating removal. Summary of the Invention

[0011] To address the above-mentioned deficiencies or improvement needs of existing technologies, this invention provides a four-axis galvanometer laser processing device that enables the laser beam to irradiate the blind hole sidewall at a sufficiently large oblique incidence angle without moving the workpiece, thereby efficiently removing the silver plating layer on the inner wall. This solves the technical problems in existing technologies where ordinary laser vertical incidence cannot effectively act on the blind hole sidewall, and where the existing oblique incidence optical path structure is complex, costly, and difficult to align.

[0012] To achieve the above objectives, according to one aspect of the present invention, a four-axis galvanometer laser processing apparatus is provided, comprising: a laser, a three-axis galvanometer scanning module, and a rotating optical path module; The laser is used to output a laser beam; The triaxial galvanometer scanning module includes a dynamic focusing unit, a first galvanometer, and a second galvanometer arranged along the optical path of the laser beam. The first galvanometer is used to control the deflection of the beam in the X-axis direction, and the second galvanometer is used to control the deflection of the beam in the Y-axis direction. The dynamic focusing unit is used to adjust the position of the laser focus in the Z-axis direction. The rotating optical path module is disposed on the output optical path of the triaxial galvanometer scanning module; the rotating optical path module includes a hollow motor, a hollow motor rotor frame and an optical component; the hollow motor rotor frame is connected to the output shaft of the hollow motor, and the optical component is disposed on the hollow motor rotor frame; The optical component includes a first reflector and a second reflector arranged sequentially along the optical path. Both the first and second reflectors are inclined relative to the rotation axis of the hollow motor, and the first and second reflectors are used to deflect the incident laser beam and emit it at a fixed tilt angle. The hollow motor is used to drive the first and second reflectors to rotate as a whole around the θ axis, so that the emitted laser beam can perform a 360° rotational scan around the rotation axis of the hollow motor.

[0013] Preferably, the rotation axis of the rotating optical path module coincides with the axis of the blind hole being processed.

[0014] Preferably, the output end of the rotating optical path module is further provided with a focusing lens, which is used to focus the laser beam passing through the rotating optical path module onto the inner wall of the blind hole.

[0015] Preferably, the focusing lens is a telecentric field lens.

[0016] Preferably, the dynamic focusing unit is a focusing lens group that can move along the optical axis, and its movement is driven by a linear motor.

[0017] Preferably, the fixed tilt angle α is greater than or equal to 30°.

[0018] Preferably, both the first reflector and the second reflector are planar reflectors.

[0019] Preferably, the hollow motor is a direct-drive motor.

[0020] Preferably, it also includes a control system, which is used to coordinate the X, Y, and Z axis movements of the triaxial galvanometer scanning module and the θ axis rotation of the rotating optical path module, so that the laser focus forms a preset scanning trajectory on the inner wall of the blind hole.

[0021] Preferably, the preset scanning trajectory is a circular scanning trajectory performed layer by layer along the depth direction of the blind hole.

[0022] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The four-axis galvanometer laser processing device proposed in this invention adopts a four-axis galvanometer system structure consisting of an "X / Y / Z three-axis galvanometer scanning module and an θ-axis rotating optical path module" to achieve oblique incidence scanning removal of the blind hole sidewall by laser. Specifically, when the hollow motor drives the reflector assembly to rotate around the optical axis, the emitted laser beam will move in a circular motion around the optical axis, that is, its tilt direction relative to the axis of the blind hole workpiece continuously changes, forming a conical scanning trajectory. Combined with the X and Y deflection control of the first and second galvanometers, the laser focus can perform circular scanning processing from the top to the bottom of the blind hole along the sidewall segment by segment, realizing the layer-by-layer removal of the silver plating layer on the entire sidewall. The four-axis galvanometer system structure of this invention replaces expensive and complex optical rotating devices such as Dove prisms and wedge lenses, making the system optical path simpler, requiring fewer precision components, and reducing manufacturing and maintenance costs.

[0023] 2. The four-axis galvanometer laser processing device proposed in this invention includes an optical component comprising a first reflecting mirror and a second reflecting mirror arranged sequentially along the optical path. Both the first and second reflecting mirrors are inclined relative to the rotation axis of the hollow motor. The optical component deflects the incident laser beam, causing it to exit at a fixed tilt angle. Due to the combined effect of the tilt of the first and second reflecting mirrors, the laser beam leaving the rotating optical path module forms a fixed tilted incident angle relative to the vertical axis of the system. By optimizing the angle arrangement of the reflecting mirrors, an incident tilt angle of 30° or even greater can be achieved, ensuring that the laser beam is sufficiently inclined to irradiate the blind hole sidewall, thereby effectively acting on the silver plating layer on the inner wall, achieving efficient removal without missing any dead corners. The laser can obliquely scour the inner wall, ablate and vaporize the silver layer, removing it completely and ensuring the quality of removal.

[0024] 3. The four-axis galvanometer laser processing device proposed in this invention requires only a single-axis rotational movement of the rotating optical path module to complete a 360° rotational scan of the laser beam direction, without involving complex multi-axis linkage and coordination control. The coordinate system of the galvanometer scan can be easily calibrated and matched with the angle of the rotating module, avoiding the problem of combined angle / position adjustment when using an optical wedge. Since there is no image rotating prism, the installation and adjustment of the system's optical axis is simpler, and the alignment and aiming of the laser optical path are easier to achieve. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the four-axis galvanometer laser processing device of the present invention.

[0026] Figure 2 This is a schematic diagram of the optical path geometry of oblique laser incidence in an embodiment of the four-axis galvanometer laser processing device of the present invention.

[0027] Figure 3 This is a schematic diagram of the structure of the three-axis galvanometer scanning module in an embodiment of the four-axis galvanometer laser processing device of the present invention.

[0028] Figure 4 This is a schematic diagram of the internal structure of the three-axis galvanometer scanning module in an embodiment of the four-axis galvanometer laser processing device of the present invention.

[0029] Figure 5 This is a schematic diagram of the internal structure of the three-axis galvanometer scanning module in an embodiment of the four-axis galvanometer laser processing device of the present invention.

[0030] Wherein: 1-shell; 2-hollow motor; 3-first reflector; 4-second reflector; 5-hollow motor rotor frame; 6-laser beam; 7-first galvanometer; 8-second galvanometer; 9-collimating lens; 10-beam expander; 11-focusing lens. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] like Figure 1-5 As shown, this invention proposes a four-axis galvanometer laser processing device, employing a four-axis galvanometer system structure consisting of X / Y / Z triaxial galvanometers and a θ-axis rotating optical path module, to achieve oblique incidence scanning removal of blind hole sidewalls by laser. The overall structure of the device is as follows. Figure 1 As shown, it includes a laser, a beam expander 10, a three-axis galvanometer scanning module, and a rotating optical path module.

[0033] Specifically, the triaxial galvanometer scanning module is a triaxial high-speed galvanometer system, such as... Figure 3 , Figure 4 and Figure 5 As shown, the system includes a beam expander 10 and a dynamic focusing unit for adjusting the focal height, as well as a first galvanometer 7 and a second galvanometer 8 that oscillate along the X and Y axes. The laser beam 6 output by the laser is expanded and collimated, and then reflected sequentially to the first galvanometer 7 and the second galvanometer 8. The focus position is adjustable by the dynamic movement of the dynamic focusing unit.

[0034] To further explain, the dynamic focusing unit can employ a movable focusing lens or a focusing lens group driven by a high-speed linear motor to adjust the focal length in the blind aperture depth direction.

[0035] Furthermore, in the rotating optical path module, the hollow motor 2 is mounted on the optical path at the output end of the triaxial galvanometer scanning module. For example... Figure 1As shown, the module is driven by a hollow shaft direct-drive motor and integrates a focusing mirror 11 and two fixed reflectors, namely the first reflector 3 and the second reflector 4. The first reflector 3 and the second reflector 4 are arranged opposite each other in the hollow motor rotor frame 5, with the tilt angle pre-designed to deflect the laser beam of the triaxial galvanometer scanning module into an outgoing beam tilted relative to the optical path axis.

[0036] Specifically, the laser beam is deflected at a certain angle after being reflected by the first reflector 3, and then reflected again by the second reflector 4 before being emitted downwards. The combination of the two reflectors ensures that the emitted laser forms a fixed angle of incidence α relative to the axis of the blind aperture. The entire reflector assembly is driven by a hollow motor 2 to rotate around the optical axis, achieving a 360° rotational scan of the laser emission direction around the axis of the blind aperture. It should be noted that the rotating optical path module does not use Dove prisms, rotating wedges, or other optical image rotators, but instead achieves beam rotation through a mechanically rotating reflector, greatly simplifying the structure and making control more intuitive and reliable.

[0037] To further explain, after passing through the triaxial galvanometer scanning module and the rotating optical path module, the laser beam is focused by the field lens (F-Theta lens) and enters the inner wall of the blind hole. The optical axis of the field lens coincides with the axis of the blind hole, and the rotating optical path module ensures that the laser beam maintains the set tilt angle α when it enters the field lens. Because the reflector assembly rotates around its axis, the focal point of the tilted laser beam after entering the field lens will trace a circular trajectory near the inner wall of the blind hole, achieving full coverage processing of the entire inner wall.

[0038] In a preferred embodiment of the present invention, the use of a telecentric field lens further ensures that the laser beam is incident on the blind hole sidewall at the same angle under different rotation angles, thereby improving the uniformity of removal. The tilt angle α is greater than or equal to 30°, which can meet the requirements for removing the silver plating layer from the inner wall of blind holes with a large depth-to-diameter ratio.

[0039] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0040] like Figure 1-3As shown, the laser beam 6 emitted by the laser is first processed by the beam expander 10 and collimator 9 to form a parallel beam of appropriate diameter, which is then directed along the optical axis towards the three-axis galvanometer scanning module. The three-axis galvanometer scanning module includes two high-speed oscillating mirrors, namely the first galvanometer 7 and the second galvanometer 8, which are vertically arranged to control the deflection of the laser beam in the X and Y directions, respectively. The galvanometers are high-speed digital galvanometers with a scanning angle range of at least ±5° to cover the target area within the blind hole cavity. After being deflected by the first galvanometer 7, the laser beam 6 is then reflected again by the second galvanometer 8 and then subjected to two-dimensional scanning offset according to a control signal. Before this, the beam enters a dynamic focusing unit, which can employ a variable focal length lens group or an electrically movable lens to adjust the laser focus position according to the blind hole depth. After dynamic focusing adjustment, the laser beam exits the three-axis galvanometer scanning module along the main optical axis and enters the subsequent rotating optical path module.

[0041] Furthermore, the rotating optical path module consists of a hollow direct-drive motor and two reflectors mounted inside the hollow motor rotor frame. The rotor of the hollow motor 2 has a hollow cylindrical structure, with its interior fixed along the diameter direction. Both reflectors are placed at an angle relative to the vertical optical axis, forming a certain angle with each other.

[0042] In one embodiment of the present invention, the first reflector 3 is tilted at 45° and the second reflector is tilted at 60°, so that the emitted laser beam has a 30° angle relative to the input optical axis. The laser beam output from the triaxial galvanometer scanning module is refracted and deflected when it passes through the first reflector 3, and then shines towards the second reflector 4. After being reflected by the second reflector 4, it is emitted downwards. Due to the combined effect of the tilted reflectors, the laser beam leaving the rotating optical path module forms a fixed tilted incident angle α relative to the vertical axis of the system. At this time, the laser beam no longer coincides with the original optical axis, but is deflected by a certain distance and emitted from the bottom of the module.

[0043] To further explain, the hollow motor 2 is driven by an θ-axis servo controller, enabling high-speed continuous rotation or precise angular positioning rotation. When the motor drives the reflector assembly to rotate around the optical axis, the emitted laser beam will move in a circular motion around the optical axis, meaning its tilt direction relative to the blind hole workpiece axis continuously changes, forming a conical scanning trajectory. If the laser emission is maintained continuously, a continuous circumferential scan can be formed on the inner wall of the blind hole. By controlling the rotation speed of the hollow motor 2 and the scanning of the galvanometer, the same scan can cover a certain annular area of ​​the inner wall of the blind hole. Combined with the X and Y deflection control of the galvanometer, the laser focus can perform a segmented annular scanning process along the sidewall from the top to the bottom of the blind hole, achieving the layer-by-layer removal of the silver plating layer on the entire sidewall.

[0044] In this embodiment of the invention, a plane focusing mirror is installed at the output end of the rotating optical path module to precisely focus the obliquely emitted laser beam onto the inner wall of the blind hole. The optical axis of the focusing mirror coincides with the axis of the blind hole, and its design ensures that the oblique beam entering the lens can still be focused into an approximately circular spot. Since the incident angle of the laser beam in this invention is relatively large (e.g., 30°), the working distance between the lens and the hole opening needs to be appropriately increased to ensure focusing effect and avoid the lens being too close to the workpiece. By controlling the coordinated movement of the galvanometer and the θ-axis rotation via computer, the laser focus can move along a predetermined path on the surface of the blind hole sidewall, achieving the scanning removal of the silver plating layer. Throughout the entire processing, the workpiece remains fixed without rotation or movement, which is particularly important for the processing of precision components.

[0045] To achieve precise machining of the system, the optical path and motion need to be calibrated and adjusted. First, adjust the position and orientation of the rotating optical path module so that its hollow shaft centerline coincides with the axis of the blind hole workpiece. Then, with rotation off, use a galvanometer to vertically strike the laser at the center of the bottom of the blind hole, fine-tuning the workpiece clamping position to ensure the laser axis is aligned with the center of the blind hole. Next, allow the θ-axis rotating module to idle for one revolution, observing the trajectory of the laser focus at the blind hole opening. If eccentricity occurs, correct it by adjusting the reflector angle or module position until the laser rotates symmetrically around the blind hole axis. Afterward, with a known incident angle α, calibrate the focus position: for example, select a reference height on the inner wall of the blind hole, control the galvanometer to strike the laser focus on the sidewall at that height, and adjust the Z-axis dynamic focusing unit until the smallest spot size and optimal energy coupling are obtained. Record this parameter as a benchmark, then verify the focusing effect at different angles, making slight compensation if necessary. Through the above calibration, establish the correspondence between the galvanometer scanning coordinates and the actual blind hole geometry.

[0046] After debugging, the silver plating layer on the inner wall of the blind hole can be removed according to the predetermined process. During processing, the control system drives the X / Y galvanometer and the θ axis to move synchronously according to the program. The hollow motor of the θ axis rotates at a constant speed, causing the laser beam to continuously rotate and sweep around the inner wall of the hole. At the same time, the deflection angle of the galvanometer is slowly moved as needed, so that the rotating spot covers the entire silver plating area row by row (or spiral by spiral). The repeated laser pulses cause the silver plating layer to be heated and vaporized or peeled off, and the molten material is carried out of the hole under the purging of protective gas. Due to the large incident angle, the laser's effect on the silver plating layer is more effective and thorough, leaving no unremoved areas on the hole wall.

[0047] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A four-axis galvanometer laser processing device, characterized in that, include: Laser, three-axis galvanometer scanning module, and rotating optical path module; The laser is used to output a laser beam (6); The triaxial galvanometer scanning module includes a dynamic focusing unit, a first galvanometer (7), and a second galvanometer (8) arranged along the optical path of the laser beam (6). The first galvanometer (7) is used to control the beam to deflect in the X-axis direction, and the second galvanometer (8) is used to control the beam to deflect in the Y-axis direction. The dynamic focusing unit is used to adjust the position of the laser focus in the Z-axis direction. The rotating optical path module is disposed on the output optical path of the triaxial galvanometer scanning module; the rotating optical path module includes a hollow motor (2), a hollow motor rotor frame (5) and an optical component; the hollow motor rotor frame (5) is connected to the output shaft of the hollow motor (2), and the optical component is disposed on the hollow motor rotor frame (5). The optical components are used to deflect the incident laser beam and emit it at a fixed tilt angle. The hollow motor (2) is used to drive the optical assembly to rotate around the θ axis, so that the emitted laser beam can perform a 360° rotation scan around the rotation axis of the hollow motor.

2. The four-axis galvanometer laser processing apparatus according to claim 1, characterized in that, The rotation axis of the rotating optical path module coincides with the axis of the blind hole being processed.

3. The four-axis galvanometer laser processing apparatus according to claim 1, characterized in that, The output end of the rotating optical path module is also provided with a focusing lens (11), which is used to focus the laser beam passing through the rotating optical path module onto the inner wall of the blind hole.

4. The four-axis galvanometer laser processing apparatus according to claim 3, characterized in that, The focusing lens (11) is a telecentric field lens.

5. The four-axis galvanometer laser processing apparatus according to claim 1, characterized in that, The dynamic focusing unit is a focusing lens group that moves along the optical axis, and its movement is driven by a linear motor.

6. The four-axis galvanometer laser processing apparatus according to claim 1, characterized in that, The fixed tilt angle α is greater than or equal to 30°.

7. The four-axis galvanometer laser processing apparatus according to claim 1, characterized in that, The optical component includes a first reflector (3) and a second reflector (4) arranged sequentially along the optical path. Both the first reflector (3) and the second reflector (4) are inclined relative to the rotation axis of the hollow motor (2). Both the first reflector (3) and the second reflector (4) are plane reflectors.

8. The four-axis galvanometer laser processing apparatus according to claim 1, characterized in that, The hollow motor (2) is a direct drive motor.

9. A four-axis galvanometer laser processing apparatus according to any one of claims 1-8, characterized in that, It also includes a control system, which is used to coordinate the X, Y, and Z axis movements of the triaxial galvanometer scanning module and the θ axis rotation of the rotating optical path module, so that the laser focus forms a preset scanning trajectory on the inner wall of the blind hole.

10. A four-axis galvanometer laser processing apparatus according to claim 9, characterized in that, The preset scanning trajectory is a circular scanning trajectory performed layer by layer along the depth direction of the blind hole.

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