A 3D printing method for reducing dynamic focusing load

Abstract

This invention relates to a 3D printing method for reducing the load of dynamic focusing, belonging to the field of 3D printing. It includes the following steps: S1. Setting a focusing field lens between the scanning galvanometer group and the printing surface; S2. Establishing a coordinate system with the position where the incident laser perpendicularly enters the printing surface as the origin; S3. Calculating the deflection angles of the X-axis and Y-axis galvanometers, and the compensation amount of the dynamic focusing lens group, based on the printing position; S4. Adjusting the X-axis and Y-axis galvanometers based on the calculation results, and adjusting the focal length using the dynamic focusing lens group to complete the printing of the corresponding coordinate points. The 3D printing method of this invention reduces the workload of the dynamic focusing motor, improves the printing quality of edge printing data, and effectively reduces the error caused by the jitter of the light spot position on the printing surface due to motor positioning jitter, thereby improving the stability of image printing.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a 3D printing method for reducing dynamic focusing load. Background Technology

[0002] Galvanometer scanning machining is widely used in various industries such as laser drilling, cutting, welding, and 3D printing. Its principle is to use a galvanometer to reflect the laser beam, scanning and printing an image on the printing surface. Based on the galvanometer scanning optical path, there are currently two methods for laser scanning focusing: front-focusing galvanometers and rear-focusing galvanometers. Rear-focusing galvanometers focus after scanning, while front-focusing galvanometers focus before scanning.

[0003] In the front-focusing galvanometer method, the laser beam first passes through a collimating lens and a beam expander, then through a dynamically adjustable focusing lens that can move in real time, and finally through the galvanometer to reflect the laser beam onto the printing surface, thus achieving laser scanning and printing. This mechanism requires the use of a program compensation algorithm to control the focusing lens in real time, and to compensate for the focal length by adjusting the position of the galvanometer scanning, so that the laser beam can be imaged onto the printing surface in real time.

[0004] The front-focusing solution uses a voice coil motor that is dynamically adjusted in real time to drive the focusing lens to focus the optical path system. Compared with the rear-focusing solution, this solution can eliminate the impact of the price and size of the F-Theta flat lens. As the 3D printing industry, which is mainly based on galvanometer scanning, matures, galvanometer printing modules are developing towards smaller size, multiple laser heads, and high integration. The front-focusing galvanometer system has the above advantages.

[0005] However, dynamic focusing currently accounts for a very small percentage of the 3D printing industry. The main reason is that dynamic focusing solutions require a voice coil motor to constantly drive the lens for position compensation. Based on actual operational needs, dynamic focusing equipment requires the lens to move back and forth to compensate for focal length over 10 billion times within a year. Therefore, it places extremely high demands on the stability of the voice coil motor and linear guide. Furthermore, the workload of the dynamic focusing motor is too heavy, and prolonged continuous operation can easily lead to failure. This limits most manufacturers from choosing front-focusing galvanometer systems. Based on current industry performance, front-focusing dynamic focusing solutions are less stable than rear-focusing flat-field lens solutions. In addition, due to the limitations of optical systems, when scanning the printed pattern, the beam's distortion is nearly twice that of rear-focusing systems when scanning the pattern center perpendicularly and the pattern edges at an angle. Therefore, the printing quality at the edges of parts is worse. Finally, the galvanometer motor, as a servo system, also experiences small-angle jitter when the reflector lens is angled. Excessive jitter can cause errors in the position of the light spot on the printing surface, affecting printing stability. Summary of the Invention

[0006] The purpose of this invention is to provide a 3D printing method that reduces the dynamic focusing load, in order to solve the problems of high workload of the dynamic focusing motor in existing focusing galvanometer systems, easy failure due to long-term uninterrupted operation, poor printing quality of parts edges, and excessive jitter when adjusting the galvanometer angle, which affects printing stability.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] This invention relates to a 3D printing method for reducing dynamic focusing load, specifically a printing method using a front focusing galvanometer system. The front focusing galvanometer system includes a dynamic focusing lens group, a scanning galvanometer group, and a printing working surface arranged sequentially according to the optical path of the incident laser. The scanning galvanometer group includes an X-axis galvanometer and a Y-axis galvanometer. The method includes the following steps:

[0009] S1. A focusing field lens is set between the scanning galvanometer group and the printing working surface, and the focusing field lens is parallel to the printing working surface;

[0010] S2. Establish a coordinate system with the position where the incident laser perpendicularly enters the printing surface as the origin;

[0011] S3. Calculate the deflection angles of the X-axis and Y-axis galvanometers, as well as the compensation amount of the dynamic focusing lens group, based on the printing position. The deflection angles of the X-axis and Y-axis galvanometers satisfy the following formula:

[0012] (1),

[0013] (2),

[0014] Where (x, y) represents the coordinates of the printing position, Dx represents the distance between the optical center of the X-axis galvanometer and the focusing field lens, Dy represents the distance between the optical center of the Y-axis galvanometer and the focusing field lens, θx and θy represent the deflection angles of the beams reflected by the X-axis and Y-axis galvanometers, respectively, L represents the vertical distance from the optical center of the scanning galvanometer group to the printing surface, and ax and ay represent the deflection angles of the beams in the X-axis and Y-axis directions after refraction by the focusing field lens, respectively.

[0015] The compensation amount of the dynamic focusing lens group is calculated using the following formula:

[0016] (5),

[0017] Where △L represents the compensation amount of the dynamic focusing lens group, and Rx and Ry represent the image field curvature radii of the surfaces where the laser beam focal points are located in the X-axis and Y-axis directions, respectively.

[0018] S4. Adjust the X-axis and Y-axis galvanometers based on the calculation results, and adjust the focal length using the dynamic focusing lens group to complete the printing of the data at the corresponding coordinate points.

[0019] Preferably, ax and ay are calculated using the following formula:

[0020] (3),

[0021] (4).

[0022] Preferably, Rx and Ry are calculated using the following formula:

[0023] (6),

[0024] (7).

[0025] Preferably, step S3, based on the calculated data of multiple sets of X-axis galvanometer deflection angles, Y-axis galvanometer deflection angles, and dynamic focusing lens group compensation amounts, obtains the functional relationship between the dynamic focusing lens group compensation amount and the X-axis and Y-axis galvanometer deflection angles through numerical simulation, and establishes a corresponding relationship data table;

[0026] In step S4, data from the relational data table is retrieved based on the coordinate points of the printed data to obtain the X-axis galvanometer deflection angle, Y-axis galvanometer deflection angle, and dynamic focusing lens group compensation amount.

[0027] Preferably, step S4 adjusts the deflection angles of the X-axis and Y-axis galvanometers via a rotary motor and drives the dynamic focusing lens group via a voice coil motor.

[0028] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0029] The 3D printing method for reducing dynamic focusing load involved in this invention adds a focusing field mirror to the front focusing galvanometer system. Based on this, the deflection angles of the X-axis and Y-axis galvanometers and the compensation amount of the dynamic focusing lens group are calculated at the printing position. Based on the calculation results, the X-axis and Y-axis galvanometers and the focal length are adjusted to reduce the focal length adjustment, reduce the workload of the dynamic focusing motor, improve the printing quality of edge printing data, and effectively reduce the error of light spot position jitter at the printing working surface caused by motor positioning jitter, thereby improving the stability of image printing. Attached Figure Description

[0030] Figure 1 is a schematic diagram of the 3D printing method for reducing dynamic focusing load according to the present invention. Detailed Implementation

[0031] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments. The following embodiments are used to illustrate the invention, but are not intended to limit the scope of the invention.

[0032] See attached document Figure 1 As shown, this invention relates to a 3D printing method for reducing dynamic focusing load, which is actually a printing method using a front focusing galvanometer system. The front focusing galvanometer system includes a dynamic focusing lens group, a scanning galvanometer group, and a printing working surface arranged sequentially according to the optical path of the incident laser. The scanning galvanometer group includes an X-axis galvanometer and a Y-axis galvanometer, and includes the following steps:

[0033] S1. A focusing field lens is set between the scanning galvanometer group and the printing working surface, and the focusing field lens is parallel to the printing working surface.

[0034] S2. Establish a coordinate system with the position where the incident laser perpendicularly enters the printing surface as the origin (0,0).

[0035] S3. Calculate the deflection angles of the X-axis and Y-axis galvanometers, as well as the compensation amount of the dynamic focusing lens group, based on the printing position. The deflection angles of the X-axis and Y-axis galvanometers satisfy the following formula:

[0036] (1),

[0037] (2),

[0038] Where (x, y) represents the coordinates of the printing position, Dx represents the distance between the X-axis galvanometer and the optical center of the focusing field lens, Dy represents the distance between the Y-axis galvanometer and the optical center of the focusing field lens, θx and θy represent the deflection angles of the X-axis and Y-axis galvanometers, respectively, L represents the perpendicular distance from the optical center of the scanning galvanometer group to the printing surface, and ax and ay represent the deflection angles of the beam in the X-axis and Y-axis directions after refraction by the focusing field lens, respectively. ax and ay are calculated using the following formula:

[0039] (3),

[0040] (4);

[0041] The compensation amount of the dynamic focusing lens group is calculated using the following formula:

[0042] (5),

[0043] Where △L represents the compensation amount of the dynamic focusing lens group, and Rx and Ry represent the image field curvature radii of the surfaces where the laser beam focal points are located in the X and Y directions, respectively. Rx and Ry are calculated using the following formulas:

[0044] (6),

[0045] (7);

[0046] S4. Based on the calculation results, the deflection angles of the X-axis and Y-axis galvanometers are adjusted by a rotary motor, and the dynamic focusing lens group is driven by a voice coil motor to adjust the focal length of the dynamic focusing lens group, thereby completing the printing of the data at the corresponding coordinate points.

[0047] In practical engineering applications, step S3, which calculates the deflection angles θx and θy of the X-axis and Y-axis galvanometers using coordinates (x, y), is typically performed using a host computer program and then printed out as data. The focal length compensation data is calculated in real-time based on the printed θx and θy. This calculation process is usually performed using an FPGA. However, FPGA memory is limited and cannot perform complex function calculations. To simplify the calculation process, this step can use multiple sets of calculated X-axis and Y-axis galvanometer deflection angles and dynamic focusing lens group compensation data to obtain the functional relationship between the dynamic focusing lens group compensation and the X-axis and Y-axis galvanometer deflection angles through numerical simulation. A relational data table is constructed regarding the deflection angle θx of the corresponding X-axis galvanometer, the deflection angle θy of the Y-axis galvanometer, and the compensation amount of the dynamic focusing lens group. Based on this, step S4 calls the data in the relational data table based on the coordinate points of the printed data to obtain the deflection angle of the X-axis galvanometer, the deflection angle of the Y-axis galvanometer, and the compensation amount of the dynamic focusing lens group.

[0048] Example of the effect: This example assumes Dx=200mm and L=500mm. Taking the data of the printed coordinate point (200,0) as an example, numerical analysis is performed, and the analysis results are as follows:

[0049] (1) When there is no focusing field lens in the optical path system, Rx=L in formula (6). From formula (1), we can get Rx=900mm. The ΔL of the focusing field lens is 21.95mm. When there is no focusing field lens, the ΔL is 38.52mm. The beam focal length value that needs to be adjusted for dynamic focusing is reduced to 57% of that without the focusing field lens.

[0050] (2) For the tilted beam, substituting the above values ​​into formula (3) we can see that αx = 0.56θx; therefore, the tilt angle of the edge beam incident on the printing surface becomes smaller compared to the front focusing system without a field lens, thereby reducing the ellipticity of the edge beam spot on the printing surface and improving the printing quality of the edge of the printing area.

[0051] (3) When the galvanometer motor is at the angle of the reflecting mirror, as a servo system, it will also experience small-angle jitter. Taking the X-axis as an example, assuming that when the rotation angle is θx, the jitter of the beam angle caused by the motor jitter is Δθx, and the jitter of the spot position on the printing surface is Δx, then the following formula is given:

[0052] (8),

[0053] In a front-focusing system without a focusing field lens, the spot position jitter Δx is given by the following formula:

[0054] (9),

[0055] Substituting the above data into formulas (8) and (9), we can obtain the following when there is a focusing field lens:

[0056] mm,

[0057] When there is no focusing field lens:

[0058] mm;

[0059] It can be seen that when the beam jitter caused by the motor is Δθx, the jitter value of the spot position at the printing surface of the optical path system with a focusing field lens is 71.5% of that of the optical path system without a field lens. This solution can effectively reduce the error of the spot position jitter at the printing surface caused by the motor positioning jitter, thereby improving the stability of image printing.

[0060] The present invention has been described in detail above with reference to the embodiments, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A 3D printing method for reducing dynamic focusing load, comprising a printing method using a front focusing galvanometer system, wherein the front focusing galvanometer system includes a dynamic focusing lens group, a scanning galvanometer group, and a printing working surface arranged sequentially according to the optical path of the incident laser, wherein the scanning galvanometer group includes an X-axis galvanometer and a Y-axis galvanometer, characterized in that, It includes the following steps: S1. A focusing field lens is set between the scanning galvanometer group and the printing working surface, and the focusing field lens is parallel to the printing working surface; S2. Establish a coordinate system with the position where the incident laser perpendicularly enters the printing surface as the origin; S3. Calculate the deflection angles of the X-axis and Y-axis galvanometers, as well as the compensation amount of the dynamic focusing lens group, based on the printing position. The deflection angles of the X-axis and Y-axis galvanometers satisfy the following formula: （1）， （2）， in,( x , y () represents the coordinates of the printing position. Dx This represents the distance between the optical center of the X-axis galvanometer and the focusing field mirror. Dy This represents the distance between the optical center of the Y-axis galvanometer and the focusing field mirror. θx and θy These represent the deflection angles of the light beams reflected by the X-axis and Y-axis galvanometers, respectively, and L represents the perpendicular distance from the optical center of the scanning galvanometer group to the printing surface. ax and ay These represent the deflection angles of the beam along the X and Y axes after refraction by the focusing field lens, respectively. The ax and ay Calculated using the following formula: （3）， （4）； The compensation amount of the dynamic focusing lens group is calculated using the following formula: （5）， Among them, △ L This indicates the compensation amount for the dynamic focusing lens group. Rx and Ry These represent the image field curvature radii of the surfaces where the laser beam focal points are located in the X and Y directions, respectively. The Rx and Ry Calculated using the following formula: （6）， （7）； S4. Adjust the X-axis and Y-axis galvanometers based on the calculation results, and adjust the focal length using the dynamic focusing lens group to complete the printing of the data at the corresponding coordinate points.

2. The 3D printing method for reducing dynamic focusing load according to claim 1, characterized in that: S3, based on the calculated data of multiple sets of X-axis galvanometer deflection angles, Y-axis galvanometer deflection angles, and dynamic focusing lens group compensation amounts, obtains the functional relationship between the dynamic focusing lens group compensation amount and the X-axis and Y-axis galvanometer deflection angles through numerical simulation, and establishes a corresponding relationship data table. In step S4, data from the relational data table is retrieved based on the coordinate points of the printed data to obtain the X-axis galvanometer deflection angle, Y-axis galvanometer deflection angle, and dynamic focusing lens group compensation amount.

3. The 3D printing method for reducing dynamic focusing load according to claim 1, characterized in that: The S4 adjusts the deflection angles of the X-axis and Y-axis galvanometers via a rotary motor and drives the dynamic focusing lens group via a voice coil motor.

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