Punching method of laser punching device

Abstract

The invention relates to a punching method of a laser punching device. The punching method comprises the following steps that (1) a workpiece is placed below a convex lens; (2) adjusting the distance between the convex lens and the surface of the workpiece; (3) punching a big-end-up conical hole; (4) judging whether the transverse size of the conical hole reaches a set size or not, if so, finishing punching, and if not, executing the next step (5); (5) adjusting the galvanometer system to enable the laser beam to move along the track; (6) the position or size of the preset track is adjusted multiple times, and machining is conducted according to the method in the step (5) after the track is adjusted every time; (7) judging whether the depth of the hole in the step (6) reaches a set depth or not, if so, executing a step (8), and if not, executing a step (9); (8) finishing punching; and (9) the distance between the convex lens and the surface of the workpiece is adjusted, and then the step (5) is returned to machine the hole in the complex shape.

Description

Technical Field

[0001] The present invention relates to the technical field of laser processing, and particularly relates to a drilling method for a laser drilling device. Background Art

[0002] With the continuous development and innovation of modern manufacturing, there are more and more processing methods for the surface of metal materials. Traditional metal surface processing methods such as mechanical cutting and stamping, although mature in technology, have limitations in processing micro-holes, complex shapes, etc. In addition, traditional processing methods are also accompanied by problems such as long processing time and a large amount of remaining waste, making it difficult to meet the requirements of high-precision micro-hole structures.

[0003] In order to meet the processing of micro-hole structures, laser processing is currently adopted. Commonly used laser processing methods include types such as CO2 laser, fiber laser, infrared laser, ultraviolet laser, etc. The processing accuracy, processing time and other parameters of different laser types are different, and the parameter adjustment can be adjusted through the control system supporting the laser, so as to further improve the accuracy and efficiency of laser processing.

[0004] Laser processing has many significant advantages, such as high precision, high quality, strong flexibility, high degree of automation, etc., so it is widely used in industrial manufacturing, aerospace, automotive and other fields. However, traditional laser processing technology mainly relies on a fixed optical path and a single movement route, which limits its application in high-precision occasions.

[0005] For example, the "Optical Device for Outer Circle Cutting" disclosed in the Chinese invention patent application with the patent application number CN201710066106.5 (publication number CN106695115A) includes a laser, a galvanometer scanner, a 4F optical system and a large-aperture focusing lens. The laser emitted by the laser enters the 4F optical system after being deflected by the galvanometer scanner. The laser changes the wavefront after passing through the 4F optical system and then enters the large-aperture focusing lens. The large-aperture focusing lens processes the laser and outputs a working laser beam with an inclination angle. The inclination angle of the working laser beam is an acute angle. The central axes of the 4F optical system and the large-aperture focusing lens coincide, and the optical axis of the laser output by the galvanometer scanner does not coincide with the central axis of the 4F optical system. The large-aperture focusing lens includes a convex lens, a plano-concave lens and a plano-convex lens arranged in sequence from front to back. The planes of the plano-concave lens and the plano-convex lens face the beam output end of the large-aperture focusing lens. When using this working laser beam with an inclination angle for drilling, the outer edge of the working laser beam will not come into contact with the workpiece to be processed, thus effectively preventing the generation of taper during drilling.

[0006] However, this patent aims to cut out circular areas rather than punch holes, and it cannot continuously process the same point to punch holes. Additionally, to prevent taper during cutting the outer circle, the angle of incidence of the light on the workpiece surface is an acute angle, which means the light diverges and cannot form special-shaped micro-holes (such as water-drop-shaped micro-holes). Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a punching method for a laser punching device capable of processing special-shaped holes in view of the current situation of the prior art.

[0008] The technical solution adopted by the present invention to solve the above technical problem is as follows: A punching method for a laser punching device, characterized in that the laser punching device includes a laser emitter, a galvanometer system, an F-theta telecentric lens, and a convex lens. The galvanometer system is arranged on the output optical path of the laser emitter to deflect the laser beam emitted by the laser emitter. The F-theta telecentric lens is arranged on the light-emitting side of the galvanometer system to focus the deflected laser beam and emit it along the vertical direction. The convex lens is arranged on the light-emitting side of the F-theta telecentric lens to focus the laser beam again.

[0009] The punching method includes the following steps:

[0010] (1) Place the workpiece below the convex lens.

[0011] (2) Adjust the distance between the convex lens and the workpiece surface to control the punching depth.

[0012] (3) Adjust the galvanometer system so that the laser beam emitted from the convex lens is vertically focused on the punching position of the workpiece to punch a tapered hole with a larger upper part and a smaller lower part.

[0013] (4) Determine whether the lateral dimension of the above tapered hole reaches the set dimension. If so, end the punching. If not, perform the next step (5).

[0014] (5) According to the shape of the preset trajectory of the laser beam projected on the F-theta telecentric lens by the galvanometer system, adjust the galvanometer system so that the laser beam moves along this trajectory to adjust the incident range of the laser beam on the convex lens. In this step, all laser beams are obliquely incident on the workpiece surface, and all laser beams pass through the position of the workpiece at the top of the tapered hole.

[0015] (6) Adjust the position or size of the preset trajectory multiple times to change the incident angle of the laser beam on the workpiece. After each adjustment of the trajectory, process according to the method in step (5) to widen the lateral dimension of the processed hole until the lateral dimension of the hole reaches the set dimension.

[0016] (7) Determine whether the hole depth in step (6) reaches the set depth. If so, execute step (8); if not, execute step (9).

[0017] (8) End the hole drilling.

[0018] (9) Adjust the distance between the convex lens and the workpiece surface to control the hole drilling depth, and then return to step (5).

[0019] In the above solution, one form is that the preset trajectory shape of the laser beam projected on the F-theta telecentric lens by the galvanometer system is circular, and the method of adjusting the preset trajectory is to change the diameter of the circular trajectory.

[0020] In the above solution, another form is that the preset trajectory of the laser beam projected on the F-theta telecentric lens by the galvanometer system is a straight line, and the method of adjusting the preset trajectory is to change the position of the straight line, but all straight lines intersect at the same point.

[0021] To facilitate the adjustment of the distance between the convex lens and the workpiece surface, the laser hole drilling device includes a first driving mechanism capable of driving the convex lens to move up and down.

[0022] Preferably, the laser hole drilling device includes a mounting table located below the convex lens for mounting the workpiece thereon, and the laser hole drilling device further includes a second driving mechanism for driving the mounting table to move in the horizontal direction. In this way, the mounting table can be driven by the driving mechanism to move to drill holes at different positions on the workpiece.

[0023] The laser emitter can adopt a fiber laser with a pulse width at the nanosecond level and a wavelength at the infrared light level.

[0024] Compared with the prior art, the advantages of the present invention are as follows: The laser beam emitted by the laser emitter of the present invention enters the galvanometer system, undergoes two optical path refractions, is emitted from the Y galvanometer to the F-theta telecentric lens, the F-theta telecentric lens focuses the laser beam, and all laser beams are vertically emitted, enter the convex lens, and perform a second focusing. According to the convex lens imaging principle, all incident light is focused into one point, and the incident range of the laser beam on the convex lens can be changed, so that the laser beam can enter the workpiece at different incident angles to process complex shapes.

[0025] In other words, the X and Y galvanometers plus the F-theta telecentric lens can be understood as simulating the size of the incident light. First, the special field lens, the F-theta telecentric lens, is used for the first focusing, and it can make the inclined incident laser beam perpendicular to the workpiece and then use a convex lens for another focusing. In order to make the micro-holes form some complex shapes, such as: water droplet shape, by changing the incident angle of the incident laser beam, it can be incident on the workpiece surface at different angles at the same focal position. After multiple processes, it can form the characteristics of a long diameter at both ends and a short diameter in the middle, so as to process the micro-holes into the ideal shape, avoiding problems such as low machining accuracy and large machining dimension deviation.

[0026] The present invention adopts the method of F-theta telecentric lens + convex lens instead of the ordinary field lens, and the hole diameter can reach the micron level of 100. This method has the following advantages: (1) The F-theta telecentric lens design can ensure that the field angle remains unchanged when observing at different focal lengths, avoiding the change of the field angle during magnification or reduction; (2) Combining the convex lens to tilt the laser beam can effectively reduce the edge distortion and parallax problems caused by the ordinary field lens; (3) The F-theta telecentric lens can make the laser beam of the lens basically parallel, resulting in a basically consistent magnification ratio of the imaging and improving the accuracy of the imaging; (4) Due to the parallel laser beam, it can be better focused during imaging and the imaging effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of the laser drilling device according to the embodiment of the present invention;

[0028] Figure 2 is Figure 1 a schematic structural diagram in another direction of

[0029] Figure 3 is a schematic diagram of the laser propagation path according to the embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of circular machining;

[0031] Figure 5 is Figure 4 a schematic diagram of the machining trajectory of

[0032] Figure 6 is a schematic diagram of linear machining;

[0033] Figure 7 is Figure 6 a schematic diagram of the machining trajectory of

[0034] Figure 8 is a schematic diagram of several holes machined by the drilling method of this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The technical solution of the present invention will be further described in detail below in conjunction with the embodiments of the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be understood that in the description of the present invention patent, unless otherwise specified, the meaning of "a plurality" is two or more. The terms "upper", "lower", "left", "right", "top", "bottom", "front", "rear", etc. indicate the orientation or positional relationship based on the direction or positional relationship shown in the drawings. It is only for the convenience of describing the present invention patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention patent.

[0037] In the description of the present invention patent, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an adhesive connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention patent can be understood according to specific circumstances.

[0038] As Figures 1 to 3 shown, the laser drilling device of this preferred embodiment includes a laser emitter 1, a galvanometer system 2, an F-theta telecentric lens 3, and a convex lens 4. In this embodiment, the laser emitter 1 uses a fiber laser with a pulse width in the nanosecond level and a wavelength in the infrared light level.

[0039] The galvanometer system 2 is arranged on the output optical path of the laser emitter 1 to deflect the laser beam emitted by the laser emitter 1. The F-theta telecentric lens 3 is arranged on the light output side of the galvanometer system 2 to focus the deflected laser beam and emit it in the direction along the plumb line. The convex lens 4 is arranged on the light output side of the F-theta telecentric lens 3 to focus the laser beam again.

[0040] In other words, the laser beam emitted by the laser emitter 1 enters the galvanometer system 2, and the optical path is deflected according to different deflection angles of the galvanometer system 2. The laser beam enters the F-theta telecentric lens 3, and after the special action of the telecentric field lens, it is emitted vertically, enters the convex lens 4, and all the laser beams are focused into one point.

[0041] The laser drilling device also includes a first drive mechanism 5 capable of driving the convex lens 4 up and down to adjust the distance between the convex lens 4 and the surface of the workpiece 9, thereby producing holes of varying depths. The first drive mechanism 5 can be a push rod motor with a push rod that can move up and down. The push rod is connected to a mounting bracket 6 on which the convex lens 4 is mounted to drive the convex lens 4 up and down. In this embodiment, the distance between the convex lens 4 and the surface of the workpiece 9 can be adjusted within a range of 10 to 20 cm.

[0042] The laser drilling device also includes a mounting platform 7 located below the convex lens 4. The mounting platform 7 is used to mount the workpiece 9 thereon. The laser drilling device also includes a second drive mechanism 8 for driving the mounting platform 7 to move horizontally. In this way, after one hole is processed, the mounting platform 7 can be driven by the second drive mechanism 8 to move to process the next hole, thereby drilling a different position on the workpiece 9.

[0043] The second driving mechanism 8 may also be a push rod motor, the push rod of the push rod motor can move in the horizontal direction, and the push rod is connected to the mounting platform 7.

[0044] The galvanometer system 2 includes an X galvanometer 21 and a Y galvanometer 22. By synchronously controlling the two galvanometers, it is possible to accurately scan the laser point on a two-dimensional plane, and to achieve high-precision laser path processing by controlling the angle change of the galvanometer. The structure and angle adjustment of the galvanometer system 2 adopt existing technologies and will not be described here. In this application, the galvanometer system is a high-speed digital scanning galvanometer (German SCANLAB technology) purchased from Hangzhou Qingshi Technology Co., Ltd., which includes control software and X galvanometer 21 and Y galvanometer 22. After entering the corresponding parameters in the control software, the X galvanometer 21 and Y galvanometer 22 can adjust the angle under the action of the control software.

[0045] Alternatively, you can also purchase a fiber laser marking machine model F3030 from Beijing Demei Yinghua System Technology Co., Ltd., which includes a laser emitter 1, a galvanometer system 2, and an F-theta telecentric lens 3. After purchasing it, you can install a convex lens 4 and a first drive mechanism 5 on it. For example, the first drive mechanism 5 is a push rod motor, and the motor of the push rod motor is fixed to the machine by screws. The mounting frame 6 for installing the convex lens 4 is connected to the push rod of the push rod motor to achieve movement and positioning after moving into place, so that the convex lens 4 is located between the F-theta telecentric lens 3 and the workpiece.

[0046] The drilling method of the laser drilling device of this embodiment includes the following steps:

[0047] The punching method comprises the following steps:

[0048] (1) placing the workpiece (9) below the convex lens (4);

[0049] (2) Adjust the distance between the convex lens (4) and the surface of the workpiece (9) to control the drilling depth;

[0050] (3) Adjust the galvanometer system (2) so that the laser beam emitted from the convex lens (4) is vertically focused on the drilling position of the workpiece (9), and a tapered hole with a larger upper part and a smaller lower part is drilled;

[0051] (4) Determine whether the lateral dimension of the above-mentioned tapered hole reaches the set dimension. If so, end the drilling. If not, perform the next step (5);

[0052] (5) According to the shape of the preset trajectory where the laser beam is projected onto the F-theta telecentric lens (3) by the galvanometer system (2), adjust the galvanometer system (2) so that the laser beam moves along this trajectory to adjust the incident range of the laser beam on the convex lens (4). In this step, all laser beams are obliquely incident on the surface of the workpiece (9), and all laser beams pass through the position of the workpiece (9) at the top of the tapered hole;

[0053] (6) Adjust the position or dimension of the preset trajectory multiple times to change the incident angle of the laser beam on the workpiece (9). After each adjustment of the trajectory, process it according to the method in step (5) to widen the lateral dimension of the processed hole until the lateral dimension of the hole reaches the set dimension;

[0054] (7) Determine whether the hole depth in step (6) reaches the set depth. If so, perform step (8). If not, perform step (9);

[0055] (8) End the drilling;

[0056] (9) Adjust the distance between the convex lens (4) and the surface of the workpiece (9) to control the drilling depth, and then return to step (5).

[0057] The following is an illustration with two different shapes of preset trajectories:

[0058] The first type:

[0059] In steps (4) and (8), the shape of the preset trajectory where the laser beam is projected onto the F-theta telecentric lens 3 by the galvanometer system 2 is circular; in steps (5) and (9), the method of adjusting the preset trajectory is to change the diameter of the circular trajectory.

[0060] See Attachment Figure 4 、 5 As shown, first vertically focus and position the laser beam on the machining position of the workpiece 9 to drill a 100-μm micro-hole ( Figure 4 the first picture in Figure 4the second figure in), and the laser beam is incident obliquely on the workpiece 9. After this trajectory is processed, the diameter of the circular trajectory is adjusted ( Figure 4 the third figure in), the distance range of the incident laser beam on the convex lens 4 is changed, thereby changing the exit angle of the laser beam and widening the size of the processed hole in the horizontal direction.

[0061] In this processing method, from Figure 4 it can be seen that the larger the diameter of the circular trajectory, the larger the processing range, and the larger the angle between the laser beam and the plumb line, which makes the diameter of the lowest end of the internal shape of the hole increase. After multiple processes, controlling the same left and right processing angle ranges will ultimately form a water-drop-shaped hole. From Figure 5 it can be seen that the final processing trajectory is multiple concentric circles.

[0062] The second method:

[0063] In steps (4) and (8), the preset trajectory shape of the laser beam projected on the F-theta telecentric lens 3 by the galvanometer system 2 is a straight line; in steps (5) and (9), the method of adjusting the preset trajectory is to change the position of the straight line, but all straight lines intersect at the same point.

[0064] First, process the laser beam along one of the straight lines of the F-theta telecentric lens 3. From Figure 6 it can be seen that as the laser beam passes through different positions of the straight line, the angle between the laser beam projected on the workpiece is different. After the laser beam moves along a straight line, change the position of the straight line. From Figure 7 it can be seen that ultimately all straight lines pass through the same point, and ultimately all straight lines form a 360° processing trajectory.

[0065] In the above two processing methods, the parameters of the fiber laser, the galvanometer system 2, the F-theta telecentric lens 3, and the convex lens 4 are as follows:

[0066] The power of the fiber laser is 200W, the galvanometer system 2 uses a 4mm aperture, the focal length of the F-theta telecentric lens 3 is 100mm, and the F-theta telecentric lens 3 is 160mm away from the surface of the workpiece 9. The processing range is 110mm x 110mm. The galvanometer system 2 is installed above, and the F-theta telecentric lens 3 is installed below, and their central axes are aligned.

[0067] The thickness of the convex lens 4 is 5mm, the focal length is 160mm, the distance between the convex lens 4 and the F-theta telecentric lens 3 is set to 100mm, and the optical axes are the same.

[0068] Both of the above two drilling methods can drill Figure 8 holes of the three shapes in, and these three shapes are only examples. The drilling method of the present invention can also drill other special-shaped holes.

[0069] In addition, during processing, the shapes of the preset trajectories in steps (4) and (8) can also be different. For example, in step (4), the shape of the preset trajectory is circular, and in step (8), the shape of the preset trajectory is linear.

Claims

1. A drilling method for a laser drilling device, characterized in that, The laser drilling device includes a laser emitter (1), a galvanometer system (2), an F-theta telecentric lens (3), and a convex lens (4). The galvanometer system (2) is arranged on the output optical path of the laser emitter (1) to deflect the laser beam emitted by the laser emitter (1). The F-theta telecentric lens (3) is arranged on the light output side of the galvanometer system (2) to focus the deflected laser beam and emit it in the direction along the plumb line. The convex lens (4) is arranged on the light output side of the F-theta telecentric lens (3) to focus the laser beam again. The drilling method includes the following steps: (1) Place the workpiece (9) below the convex lens (4). (2) Adjust the distance between the convex lens (4) and the surface of the workpiece (9) to control the drilling depth. (3) Adjust the galvanometer system (2) so that the laser beam emitted from the convex lens (4) is vertically focused on the drilling position of the workpiece (9) to drill a tapered hole with a larger upper part and a smaller lower part. (4) Judge whether the lateral dimension of the above-mentioned tapered hole reaches the set dimension. If so, end the drilling. If not, execute the next step (5). (5) According to the shape of the preset trajectory of the laser beam projected on the F-theta telecentric lens (3) by the galvanometer system (2), adjust the galvanometer system (2) so that the laser beam moves along this trajectory to adjust the incident range of the laser beam on the convex lens (4). In this step, all laser beams are obliquely incident on the surface of the workpiece (9), and all laser beams pass through the position of the workpiece (9) at the top of the tapered hole. (6) Adjust the position or size of the preset trajectory multiple times to change the incident angle of the laser beam on the workpiece (9). After each adjustment of the trajectory, process according to the method of step (5) to widen the lateral dimension of the processed hole until the lateral dimension of the hole reaches the set dimension. (7) Judge whether the depth of the hole in step (6) reaches the set depth. If so, execute step (8). If not, execute step (9). (8) End the drilling. (9) Adjust the distance between the convex lens (4) and the surface of the workpiece (9) to control the drilling depth, and then return to step (5).

2. The punching method according to claim 1, wherein: The shape of the preset trajectory of the laser beam projected on the F-theta telecentric lens (3) by the galvanometer system (2) is circular, and the method of adjusting the preset trajectory is to change the diameter of the circular trajectory.

3. The punching method according to claim 1, characterized in that: The shape of the preset trajectory of the laser beam projected on the F-theta telecentric lens (3) by the galvanometer system (2) is a straight line, and the method of adjusting the preset trajectory is to change the position of the straight line, but all straight lines intersect at the same point.

4. The punching method according to claim 1, characterized in that: The adjustable range of the distance between the convex lens (4) and the surface of the workpiece (9) is between 10 and 20 cm.

5. The punching method according to any one of claims 1 to 4, characterized in that: The laser drilling device includes a first driving mechanism (5) capable of driving the convex lens (4) to move up and down.

6. The punching method according to claim 5, wherein: The convex lens (4) is installed on the mounting frame (6). The first driving mechanism (5) is a push rod motor. The push rod of the push rod motor can move up and down, and the push rod is connected to the mounting frame (6) for mounting the convex lens (4) to drive the convex lens (4) to move up and down.

7. The punching method according to any one of claims 1 to 4, characterized in that: The laser drilling device includes a mounting table (7) located below the convex lens (4), and the mounting table (7) is used for mounting the workpiece (9) thereon. The laser drilling device further includes a second driving mechanism (8) for driving the mounting table (7) to move horizontally.

8. The punching method according to claim 7, wherein: The second driving mechanism (8) is a push rod motor, and the push rod of the push rod motor can move horizontally and is connected to the mounting table (7).

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