3D printing method for reducing dynamic focusing load

Abstract

The invention relates to a 3D printing method for reducing dynamic focusing load, which belongs to the field of 3D printing and comprises the following steps: S1, a focusing field lens is arranged between a scanning galvanometer group and a printing working surface; s2, establishing a coordinate system by taking the position where the incident laser vertically enters the printing working surface as a coordinate origin; s3, deflection angles of an X-axis galvanometer and a Y-axis galvanometer and the compensation amount of a dynamic focusing lens group are calculated based on the printing position; and S4, the X-axis galvanometer and the Y-axis galvanometer are adjusted based on the calculation result, the focal length is adjusted through a dynamic focusing lens set, and printing of the printing data on the corresponding coordinate points is completed. According to the 3D printing method, the working load of the dynamic focusing motor is reduced, the printing quality of edge printing data is improved, the error of light spot position jittering at the printing working face caused by motor positioning jittering is effectively reduced, and therefore the stability of image printing is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of 3D printing, and in particular relates to a 3D printing method for reducing dynamic focusing load. Background Art

[0002] Galvanometer scanning processing is widely used in laser drilling, cutting, welding, 3D printing and other industries. Its principle is to use a galvanometer to reflect the laser beam and perform image scanning and printing on the printing work surface. According to the galvanometer scanning light path, the current laser scanning focusing methods include front focusing galvanometer and rear focusing galvanometer. The rear focusing galvanometer focuses after scanning, and the front focusing galvanometer focuses before scanning.

[0003] Among them, in the front focusing galvanometer method, the laser beam first passes through the collimator and beam expander, then through the dynamic focusing lens that can move in real time, and then through the galvanometer to reflect the laser to achieve the scanning and printing of the laser on the printing work surface. This mechanism needs to use a program compensation algorithm to control the focusing lens in real time, and coordinate the position of the galvanometer scanning to compensate the focal length, so that the laser beam can be imaged on the printing work surface in real time.

[0004] The front focusing solution uses a voice coil motor that is adjusted dynamically 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-field lens. As the 3D printing industry based on galvanometer scanning matures, the galvanometer printing module is developing towards small size, multiple laser heads, and high integration. The front focusing galvanometer system has the above advantages.

[0005] However, it currently accounts for a very low proportion in the 3D printing industry. The main reason is that the dynamic focus solution requires the voice coil motor to drive the lens to perform position compensation at all times. According to the actual work requirements, the dynamic focus device requires the lens to move back and forth to compensate the focal length more than 10 billion times within a year's working period. Therefore, it has very high requirements for the stability of the voice coil motor and the linear guide. In addition, the workload of the dynamic focus motor is too large, and it is easy to fail if it works uninterruptedly for a long time. Therefore, most manufacturers are restricted from choosing the front-focusing galvanometer system. According to the actual performance of current products in the industry, the front-focusing dynamic focus solution is less stable than the rear-focusing flat-field lens solution. In addition, the front-focusing system is limited by the principle of the optical system. When scanning the printed pattern, the beam vertically scans the center position of the pattern and the beam tilts the edge position of the pattern. The deformation of the light spot is close to twice that of the rear-focusing system, so the quality of the edge printing of its parts is worse. Finally, when the galvanometer motor reflects the angle of the lens, as a servo system, it will also have a small angle of jitter. Excessive jitter will cause errors in the jitter of the light spot position at the printing work surface, affecting the stability of printing. Summary of the invention

[0006] The purpose of the present invention is to provide a 3D printing method for reducing the dynamic focus load, so as to solve the problems that the dynamic focus motor of the existing focusing galvanometer system has a large workload, is prone to failure during long-term uninterrupted operation, the quality of printing on the edges of parts is worse, and the jitter is too large when adjusting the galvanometer angle, affecting the printing stability.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows: The present invention relates to a 3D printing method for reducing dynamic focus load, which is a printing method of a front focusing galvanometer system. The front focusing galvanometer system comprises a dynamic focus lens group, a scanning galvanometer group and a printing work surface which are sequentially arranged according to the optical path of an incident laser. The scanning galvanometer group comprises an X-axis galvanometer and a Y-axis galvanometer. The method comprises the following steps: S1. A focusing field lens is set between the scanning galvanometer group and the printing work surface, and the focusing field lens is parallel to the printing work surface; S2. Establish a coordinate system with the position where the incident laser vertically enters the printing work surface as the coordinate origin; S3. Calculate the deflection angles of the X-axis galvanometer and the Y-axis galvanometer based on the printing position, and the compensation amount of the dynamic focus lens group, wherein the deflection angles of the X-axis galvanometer and the Y-axis galvanometer satisfy the following formula: (1), (2), Wherein, (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 light beam after reflection from the X-axis galvanometer and the Y-axis galvanometer, L represents the vertical distance from the optical center of the scanning galvanometer group to the printing work surface, and ax and ay represent the deflection angles of the light beam in the X-axis and Y-axis directions after refraction by the focusing field lens, respectively; The compensation amount of the dynamic focus lens group is calculated by the following formula: (5), Wherein, △L represents the compensation amount of the dynamic focus lens group, and Rx and Ry represent the image field curvature radius of the curved surface where the laser beam focusing point is located in the X-axis and Y-axis directions, respectively; S4. Based on the calculation results, the X-axis galvanometer and the Y-axis galvanometer are adjusted, and the focal length is adjusted using the dynamic focus lens group to complete the printing of the print data at the corresponding coordinate point.

[0008] Preferably, ax and ay are calculated by the following formula: (3), (4).

[0009] Preferably, the Rx and Ry are calculated by the following formula: (6), (7).

[0010] Preferably, S3 obtains the functional relationship between the dynamic focus lens group compensation amount and the deflection angles of the X-axis galvanometer and the Y-axis galvanometer based on the calculated data of the multiple groups of X-axis galvanometer deflection angles, the Y-axis galvanometer deflection angles and the dynamic focus lens group compensation amount through numerical simulation, and establishes a corresponding relationship data table; In the S4, the data in the relational data table is called based on the coordinate points of the print data to obtain the X-axis galvanometer deflection angle, the Y-axis galvanometer deflection angle and the dynamic focus lens group compensation amount.

[0011] Preferably, the S4 adjusts the deflection angles of the X-axis galvanometer and the Y-axis galvanometer by a rotating motor, and drives the dynamic focus lens group by a voice coil motor.

[0012] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The 3D printing method for reducing dynamic focus load involved in the present invention adds a focusing field mirror on the basis of a front focusing galvanometer system, calculates the printing position, calculates the deflection angles of the X-axis galvanometer and the Y-axis galvanometer, and the compensation amount of the dynamic focus lens group on this basis, adjusts the X-axis galvanometer, the Y-axis galvanometer and the focal length based on the calculation results, reduces the focal length adjustment, reduces the workload of the dynamic focus motor, improves the printing quality of edge printing data, effectively reduces the error of the light spot position jitter at the printing working surface caused by the motor positioning jitter, thereby improving the stability of image printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a schematic diagram of a 3D printing method for reducing dynamic focus load according to the present invention. DETAILED DESCRIPTION

[0014] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0015] Refer to the attached Figure 1 As shown, the present invention relates to a 3D printing method for reducing dynamic focus load, which is actually a printing method of a front focusing galvanometer system. The front focusing galvanometer system includes a dynamic focus lens group, a scanning galvanometer group and a printing work surface arranged in sequence according to the optical path of the incident laser, and the scanning galvanometer group includes an X-axis galvanometer and a Y-axis galvanometer, which includes the following steps: S1. A focusing field lens is arranged between the scanning galvanometer group and the printing work surface, and the focusing field lens is parallel to the printing work surface.

[0016] S2. Establish a coordinate system with the position where the incident laser vertically enters the printing work surface as the coordinate origin (0,0).

[0017] S3. Calculate the deflection angles of the X-axis galvanometer and the Y-axis galvanometer based on the printing position, and the compensation amount of the dynamic focus lens group, wherein the deflection angles of the X-axis galvanometer and the Y-axis galvanometer satisfy the following formula: (1), (2), Wherein, (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 galvanometer and the Y-axis galvanometer, respectively, L represents the vertical distance from the optical center of the scanning galvanometer group to the printing work surface, ax and ay represent the deflection angles of the light beam in the X-axis and Y-axis directions after refraction by the focusing field lens, respectively, and ax and ay are calculated by the following formula: (3), (4); The compensation amount of the dynamic focus lens group is calculated by the following formula: (5), Wherein, △L represents the compensation amount of the dynamic focus lens group, Rx and Ry represent the image field curvature radius of the curved surface where the laser beam focus point is located in the X-axis and Y-axis directions, respectively, and Rx and Ry are calculated by the following formula: (6), (7); S4. Based on the calculation results, the deflection angles of the X-axis galvanometer and the Y-axis galvanometer are adjusted by rotating the motor, and the dynamic focus lens group is driven by the voice coil motor to adjust the focal length of the dynamic focus lens group to complete the printing of the print data at the corresponding coordinate point.

[0018] In actual engineering applications, step S3 calculates the deflection angle θx of the X-axis galvanometer and the deflection angle θy of the Y-axis galvanometer through the coordinates (x, y), which is usually calculated using a host computer program and sent down as print data. The focal length compensation data is calculated in real time based on the sent θx and θy. This calculation process is usually performed using FPGA. The FPGA memory is limited and complex functions cannot be calculated. In order to simplify the calculation process, this step can be based on the calculated data of multiple groups of X-axis galvanometer deflection angles, Y-axis galvanometer deflection angles and dynamic focus lens group compensation amounts, and the functional relationship between the dynamic focus lens group compensation amount and the deflection angles of the X-axis galvanometer and the Y-axis galvanometer can be obtained through numerical simulation. , and construct a relationship data table about the corresponding X-axis galvanometer deflection angle θx, Y-axis galvanometer deflection angle θy and compensation amount of the dynamic focus lens group; on this basis, step S4 calls the data in the relationship data table based on the coordinate point of the print data to obtain the X-axis galvanometer deflection angle, Y-axis galvanometer deflection angle and compensation amount of the dynamic focus lens group.

[0019] Effect example: This effect example assumes that Dx=200mm, L=500mm, and takes the data of the printing coordinate point (200,0) as an example for numerical analysis. The analysis results are as follows: (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 focal length of the beam required to be adjusted for dynamic focusing is reduced to 57% of that without the focusing field lens.

[0020] (2) For the inclined beam, substituting the above values ​​into formula (3), it can be seen that αx=0.56θx; therefore, the inclination angle of the edge beam incident on the printing work surface becomes smaller than that of the front focusing system without a field lens, thereby reducing the ellipticity of the edge beam spot on the printing work surface and improving the printing quality at the edge of the printing format.

[0021] (3) When the galvanometer motor is used as a servo system, it will also experience small-angle jitter when the angle of the reflective lens changes. Taking the X-axis as an example, assuming that when the rotation angle is θx, the beam angle jitter value caused by the motor jitter is Δθx, and the spot position jitter of this value on the printing work surface is Δx, then the following formula is obtained: (8), For a front focusing system without a focusing field lens, the light spot position jitter Δx has the following formula: (9), Substituting the above data into formulas (8) and (9) we can obtain that when there is a focusing field lens: mm, When there is no focusing field lens: mm; It can be seen from this that when the beam jitter value caused by the motor is Δθx, the jitter value of the light spot position at the printing work 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 scheme can effectively reduce the error of the light spot position jitter at the printing work surface caused by the motor positioning jitter, thereby improving the stability of image printing.

[0022] The present invention is described in detail above in conjunction with the embodiments, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A 3D printing method for reducing dynamic focus load, which is a printing method of a front focusing galvanometer system, wherein the front focusing galvanometer system comprises a dynamic focus lens group, a scanning galvanometer group and a printing work surface arranged in sequence according to the optical path of the incident laser, wherein the scanning galvanometer group comprises an X-axis galvanometer and a Y-axis galvanometer, and is characterized in that: It includes the following steps: S1. A focusing field lens is set between the scanning galvanometer group and the printing work surface, and the focusing field lens is parallel to the printing work surface; S2. Establish a coordinate system with the position where the incident laser vertically enters the printing work surface as the coordinate origin; S3. Calculate the deflection angles of the X-axis galvanometer and the Y-axis galvanometer based on the printing position, and the compensation amount of the dynamic focus lens group, wherein the deflection angles of the X-axis galvanometer and the Y-axis galvanometer satisfy the following formula: （1）， （2）， Wherein, (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 light beam after reflection from the X-axis galvanometer and the Y-axis galvanometer, L represents the vertical distance from the optical center of the scanning galvanometer group to the printing work surface, and ax and ay represent the deflection angles of the light beam in the X-axis and Y-axis directions after refraction by the focusing field lens, respectively; The compensation amount of the dynamic focus lens group is calculated by the following formula: （5）， Wherein, △L represents the compensation amount of the dynamic focus lens group, and Rx and Ry represent the image field curvature radius of the curved surface where the laser beam focusing point is located in the X-axis and Y-axis directions, respectively; S4. Based on the calculation results, the X-axis galvanometer and the Y-axis galvanometer are adjusted, and the focal length is adjusted using the dynamic focus lens group to complete the printing of the print data at the corresponding coordinate point.

2. The 3D printing method for reducing dynamic focus load according to claim 1, characterized in that: The ax and ay are calculated by the following formula: （3）， （4）。 3. The 3D printing method for reducing dynamic focus load according to claim 1, characterized in that: The Rx and Ry are calculated by the following formula: （6）， （7）。 4. The 3D printing method for reducing dynamic focus load according to claim 1, characterized in that: S3 obtains the functional relationship between the dynamic focus lens group compensation amount and the deflection angles of the X-axis galvanometer and the Y-axis galvanometer based on the calculated data of the multiple groups of X-axis galvanometer deflection angles, the Y-axis galvanometer deflection angles and the dynamic focus lens group compensation amount through numerical simulation, and establishes a corresponding relationship data table; In the S4, the data in the relational data table is called based on the coordinate points of the print data to obtain the X-axis galvanometer deflection angle, the Y-axis galvanometer deflection angle and the dynamic focus lens group compensation amount.

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

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