Laser melting powder metal 3D printing method

Abstract

The present invention discloses a laser melting powder metal 3D printing method, comprising the following steps: A1, comparing the range of the next layer of graphics to be printed with the printed previous layer of graphics in horizontal projection, if all the graphics of the next layer are within the range of the graphics of the previous layer, using the melting printing method to print all the graphics of the next layer, otherwise executing step A2; A2, for the part of the graphics of the next layer within the range of the graphics of the previous layer, using the melting printing method to print, for the part of the graphics of the next layer outside the range of the graphics of the previous layer, using the sintering printing method to print, wherein, during the sintering printing process, relying on powder support to complete the structural molding of the part outside the range. The present invention realizes that in the printing process of objects with suspended structures and bevel angles, the support structure can be used without or with less use, and the printing efficiency is improved, and the workload of post-processing is reduced.

Description

Technical Field

[0001] The invention relates to the field of laser melting powder spreading metal 3D printing, and in particular to a laser melting powder spreading metal 3D printing method. Background Art

[0002] Laser melting powder 3D printing uses a method of layering powder and then using laser melting a two-dimensional plane path to achieve the printing and forming of a three-dimensional structure. In actual printing applications, it is often necessary to add various types of support structures to suspended and inclined structures to ensure complete forming. However, the use of support structures consumes printing materials and increases printing time. Therefore, there is a demand for application development of metal 3D printing process methods with no or few support structures. However, the unsupported printing function faces challenges such as difficulty in implementation and lack of versatility in laser melting powder metal 3D printing. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that laser melting powder metal 3D printing is difficult to achieve unsupported printing function, and to propose a laser melting powder metal 3D printing method.

[0004] The following technical solutions are used to solve this problem:

[0005] A laser melting powder metal 3D printing method comprises the following steps:

[0006] A1, compare the range of the next layer of graphics to be printed with the range of the previous layer of graphics printed on the horizontal projection, if all the graphics of the next layer are within the range of the graphics of the previous layer, use the melting printing method to print all the graphics of the next layer, otherwise execute step A2;

[0007] A2. For the portion of the graphics of the next layer that is within the range of the graphics of the previous layer, the melting printing method is used for printing, and for the portion of the graphics of the next layer that is outside the range of the graphics of the previous layer, the sintering printing method is used for printing, wherein during the sintering printing process, the structural forming of the portion outside the range is completed by relying on powder support.

[0008] In some embodiments, in step A2, the range of the graphics of the next layer completely covers the graphics of the previous layer, or only partially covers the graphics of the previous layer.

[0009] In some embodiments, during printing, the laser beam emitted by the laser is expanded and shaped before being incident on a scanning galvanometer, and then focused onto a molding substrate covered with metal powder through a focusing field lens, wherein the scanning galvanometer is controlled by a software slicing layer to scan a two-dimensional pattern on the molding substrate to print the metal powder into shape.

[0010] In some embodiments, during printing, the scanning angle of the scanning galvanometer is controlled to be within a set angle value according to a predetermined printing scanning strategy.

[0011] In some embodiments, before printing a layer, the powder spreading shaft spreads the metal powder on the molding substrate through a scraper. After printing a layer, the molding substrate is controlled to drop the distance of the slice layer thickness, and the powder spreading shaft spreads powder on the molding substrate again to prepare for printing the next layer.

[0012] In some embodiments, the metal powder is applied to a thickness of 30-100 μm.

[0013] In some embodiments, the scraper is a soft or hard scraper.

[0014] In some embodiments, the laser is a continuous type light source with a wavelength of infrared or green light and a power of 100W-500W.

[0015] In some embodiments, the printing parameters for controlling the printing of each layer include at least laser power, laser beam scanning speed, filling pitch, and scanning angle.

[0016] The beneficial effects of the present invention compared with the prior art include:

[0017] The present invention proposes a laser melting powder metal 3D printing method, which compares the range of the next layer of graphics to be printed and the printed previous layer of graphics in horizontal projection during the printing process. If it is determined that all the graphics of the next layer are within the range of the graphics of the previous layer, all the graphics of the next layer are printed using a melting printing method. If it is determined that the graphics of the next layer exceed the range of the graphics of the previous layer, the part of the graphics of the next layer that is within the range of the graphics of the previous layer is printed using a melting printing method, and the part of the graphics of the next layer that is outside the range of the graphics of the previous layer is printed using a sintering printing method. In this way, in the printing process of objects with suspended structures and bevel angles, the support structure can be omitted or reduced, the printing efficiency is improved, the workload of post-processing is reduced, the process has high versatility and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of a laser melting powder metal 3D printing method according to an embodiment of the present invention;

[0019] Figure 2 It is a layered flow chart of a laser melting powder metal 3D printing method in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described below with reference to the accompanying drawings and in combination with preferred embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0021] It should be noted that the directional terms such as left, right, up, down, top, and bottom in this embodiment are merely relative concepts or are based on the normal use status of the product, and should not be considered as restrictive.

[0022] The embodiment of the present invention provides a laser melting powder metal 3D printing method capable of achieving support-free printing.

[0023] The following is an overview of embodiments of the present invention:

[0024] like Figure 1 As shown, the laser melting powder metal 3D printing method in the embodiment of the present invention includes the following steps:

[0025] A1, compare the range of the next layer of graphics to be printed with the range of the previous layer of graphics printed on the horizontal projection, if all the graphics of the next layer are within the range of the graphics of the previous layer, use the melting printing method to print all the graphics of the next layer, otherwise execute step A2;

[0026] A2. For the portion of the graphics of the next layer that is within the range of the graphics of the previous layer, the melting printing method is used for printing, and for the portion of the graphics of the next layer that is outside the range of the graphics of the previous layer, the sintering printing method is used for printing, wherein during the sintering printing process, the structural forming of the portion outside the range is completed by relying on powder support.

[0027] In step A2, the range of the graphics of the next layer completely covers the graphics of the previous layer, or only partially covers the graphics of the previous layer.

[0028] Specifically during printing, the laser beam emitted by the laser is expanded and shaped before being incident on the scanning galvanometer, and then focused onto the molding substrate covered with metal powder through the focusing field lens. The scanning galvanometer is controlled by the software slicing layer to scan the two-dimensional pattern on the molding substrate to print the metal powder.

[0029] The focusing field lens is an optical lens that focuses the laser beam onto the surface of the molding substrate; the scanning galvanometer is used to scan the laser beam and print each layer of two-dimensional graphics on the molding substrate; the molding substrate is the substrate for 3D printing, which is used to fix and support the entire printed sample. The laser can use a continuous type light source, the wavelength can be infrared or green light, and the power can be selected from 100W to 500W.

[0030] During printing, the scanning angle of the scanning galvanometer can be further controlled to be within a set angle value according to a predetermined printing scanning strategy.

[0031] Before printing a layer, the powder-spreading shaft can further spread the metal powder on the molding substrate through a scraper. After printing a layer, the molding substrate is controlled to drop by a distance of the slice layer thickness, and the powder-spreading shaft spreads powder on the molding substrate again to prepare for printing the next layer.

[0032] The thickness of the metal powder spread on the molding substrate can be selected to be 30-100 μm.

[0033] During specific implementation, the scraper in the powder spreading shaft can be a soft or hard scraper.

[0034] In a specific implementation, the printing parameters for controlling the printing of each layer include at least laser power, laser beam scanning speed, filling spacing, and scanning angle.

[0035] Example:

[0036] The laser melting powder metal 3D printing method provided in the embodiment of the present invention comprises the following steps:

[0037] The laser beam emitted from a continuous laser is expanded and shaped before entering the scanning galvanometer, and then focused onto the printed substrate by a focusing field lens.

[0038] The powder-spreading shaft spreads 30-100um metal powder on the printing substrate through a scraper, and the scanning galvanometer scans the two-dimensional graphics on the molding substrate according to the software slice layer for printing. After printing a layer, the molding substrate drops the slice layer thickness distance, and the powder-spreading shaft spreads powder on the molding substrate again. The printing software compares the position and area of ​​the next printing layer. If the area of ​​the second layer is smaller than that of the first layer, and the second layer area is within the range of the first layer, the printing parameters of the second layer are the same as those of the first layer and are also parameter A. If the area of ​​the second layer is larger than that of the first layer, the printing parameters of the second layer will be divided into two parts. The printing parameters of the same area as the first layer are parameter A, and the printing parameters of the remaining areas will be parameter B. Each subsequent layer is calculated by analogy with this algorithm.

[0039] The specific implementation steps of the laser melting powder metal 3D printing method in this embodiment are as follows:

[0040] This embodiment adopts a process method to perform conventional laser melting 3D printing on the powder material of the suspended structural parts, which can help reduce or carry out metal 3D printing without support. A continuous laser is used, and a scanning galvanometer is used to scan the graphics of the powder material laid flat on the base plate. The printing software compares the position and area of ​​the printed graphics of each layer with the graphics of the previous layer, and the software sets the printing parameters for each layer or specific area. The area of ​​the first layer of graphics to be printed on the molding base plate is set to S1, the area of ​​the second layer of graphics is set to S2, the area of ​​the third layer of graphics is set to S3, ..., and so on. The area of ​​the nth layer of graphics is set to Sn. Several process parameter packages of the equipment are determined through process tests, such as setting the parameters for completely melting and printing the powder material to process parameter package A, and setting the printing parameters for sintering the powder material to process parameter package B.

[0041] Among them, fusion printing is to completely melt the powder, and the bottom surface needs to have a solid support, while sintering printing is to partially melt the powder and condense it into a block, and the bottom surface can be a powder support.

[0042] The software algorithm of the embodiment of the present invention is to compare the area and region of each printed layer with the previous layer. For example, if the printing parameters of the first layer are the melting printing process parameters A, if the area of ​​the second layer is smaller than that of the first layer, and the area of ​​the second layer is within the range of the first layer, the printing parameters of the second layer are the same as those of the first layer and are also the sintering printing process parameters A. If the area of ​​the second layer is larger than that of the first layer, the printing parameters of the second layer will be divided into two parts, and the printing parameters of the same area as the first layer will be the melting printing process parameters A, and the printing parameters of the remaining areas will be the sintering printing process parameters B. Each subsequent layer is calculated by analogy with this algorithm.

[0043] The laser melting powder metal 3D printing method proposed in the embodiment of the present invention has the following beneficial effects:

[0044] The process adopted in the embodiment of the present invention calculates and compares the position and area of ​​each layer of printed graphics through software when performing metal powder 3D printing, adopts sintering printing process parameters for the area where the printed layer is suspended in the bottom layer, relies on the support of the powder itself to form a structural molding, and adopts melting printing process parameters in the position area with solid support to achieve the dense performance of the printed object; in this way, in the process of printing some objects with suspension and bevel angles, it is unnecessary or unnecessary to add support structures, thereby improving printing efficiency and reducing post-processing work.

[0045] Experimental example

[0046] The laser melting powder metal 3D printing process used in the experimental example of the present invention includes:

[0047] A 300W infrared fiber laser with a wavelength of 1080nm is used. The process parameters are set using power percentage. The metal powder used in the example is 316L stainless steel powder.

[0048] For example, when printing graphics on a molded substrate, the parameters used are 55% power, i.e., 165W power, 400mm / s scanning speed, 0.1mm filling spacing, and 67° scanning angle. 55-400-0.1-67° will be used to describe the overall setting parameters.

[0049] Through process debugging, the laser melting full printing parameter package A1 is 165W power, 400mm / s scanning speed, 0.1mm filling spacing, and 67° scanning angle;

[0050] Through process debugging, the laser melting full printing parameter package A2 is 165W power, 400mm / s scanning speed, 0.1mm filling spacing, and 157° scanning angle;

[0051] Through process debugging, the laser sintering printing parameter package B1 is set to 180W power, 1200mm / s scanning speed, 0.1mm filling spacing, and 67° scanning angle;

[0052] Through process debugging, the laser sintering printing parameter package B2 is set to 180W power, 1200mm / s scanning speed, 0.1mm filling spacing, and 157° scanning angle;

[0053] The parameters of the scanning angle are related to the scanning strategy of printing, which affects the overall appearance and performance of the printed product. For example, in the printing process, the scanning angle of each layer is orthogonal. If the scanning angle of one layer is 67 degrees, the scanning angle of the next layer is 157 degrees, so the parameters of A1 and A2 are different.

[0054] Parameter A can achieve complete melting of metal powder to achieve a densified effect; parameter B can achieve partial melting and condensation of metal powder to achieve sintering of powder into a solid structure;

[0055] like Figure 2 As shown, the area of ​​the first layer of graphics printed on the molding substrate is S1, and the software calls the printing parameter package A1 for printing;

[0056] The area of ​​the second layer of graphics printed on the molding substrate is S2. If the second layer of graphics is within the range of the first layer of graphics and the area S2≤S1, the second layer of graphics printing parameters adopt parameter A2; if the second layer of graphics is outside the first layer of graphics, the software calls parameter package A2 for printing the graphics with the same position and area as the first layer, and calls parameter B2 for printing other newly added areas;

[0057] The area of ​​the third layer of graphics printed on the molding substrate is S3. If the position of the third layer of graphics is within the range of the second layer of graphics and the area S3≤S2, the third layer of printing graphics parameters adopt parameter A1; if the position of the third layer of graphics is outside the second layer of graphics, the software calls parameter package A1 for printing the graphics position and area that are the same as the second layer, and calls parameter B1 for printing other newly added areas;

[0058] When the area of ​​the n-th layer of graphics printed on the molding substrate is Sn and n is an odd number, if the position of the n-th layer of graphics is within the range of the n-1 layer of graphics and the area Sn≤Sn-1, the n-th layer of graphics printing parameters adopts parameter A1; if the position of the n-th layer of graphics is outside the n-1 layer of graphics, the software calls parameter package A1 for printing the graphics with the same position and area as the n-th layer, and calls parameter B1 for printing other newly added areas;

[0059] When the area of ​​the nth layer of graphics printed on the molding substrate is Sn and n is an even number, if the position of the nth layer of graphics is within the range of the n-1th layer of graphics and the area Sn≤Sn-1, the nth layer of graphics printing parameters adopt parameter A2; if the position of the nth layer of graphics is outside the n-1th layer of graphics, the software calls parameter package A2 for printing the graphics with the same position and area as the nth layer, and calls parameter B2 for printing other newly added areas;

[0060] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A laser melting powder metal 3D printing method, characterized in that: The steps include: A1, calculate and compare the position and area of ​​each layer of printed graphics, and compare the range of the graphics of the next layer to be printed with the graphics of the previous layer in horizontal projection. If all the graphics of the next layer are within the range of the graphics of the previous layer, use the full fusion printing method to print all the graphics of the next layer, otherwise execute step A2; A2. For the part of the graphics of the next layer that is within the range of the graphics of the previous layer, a fully fused printing method is used for printing, so that the position area with solid support can achieve the dense performance of the printed object. For the part of the graphics of the next layer that is outside the range of the graphics of the previous layer, a sintering printing method is used to partially melt the metal powder for printing, so that the supporting structure of the suspended area in the bottom layer is reduced or not added during printing, wherein, during the partially fused sintering printing process, the structural molding of the part outside the range is completed by relying on powder support.

2. The laser melting powder metal 3D printing method according to claim 1, characterized in that: In step A2, the range of the graphics of the next layer completely covers the graphics of the previous layer, or only partially covers the graphics of the previous layer.

3. The laser melting powder metal 3D printing method according to claim 1 or 2, characterized in that: During printing, the laser beam emitted by the laser is expanded and shaped before being incident on the scanning galvanometer, and then focused onto the molding substrate covered with metal powder through the focusing field lens. The scanning galvanometer is controlled by the software slicing layer to scan the two-dimensional pattern on the molding substrate to print the metal powder.

4. The laser melting powder metal 3D printing method according to claim 3, characterized in that: During printing, the scanning angle of the scanning galvanometer is controlled to be within a set angle value according to a predetermined printing scanning strategy.

5. The laser melting powder metal 3D printing method according to claim 3, characterized in that: Before printing a layer, the powder spreading shaft spreads the metal powder on the molding substrate through a scraper. After printing a layer, the molding substrate is controlled to drop by a distance of the slice layer thickness, and the powder spreading shaft spreads powder on the molding substrate again to prepare for printing the next layer.

6. The laser melting powder metal 3D printing method according to claim 5, characterized in that: The thickness of the metal powder spread is 30-100 μm.

7. The laser melting powder metal 3D printing method according to claim 5, characterized in that: The scraper is a soft or hard scraper.

8. The laser melting powder metal 3D printing method according to claim 1 or 2, characterized in that: The laser is a continuous type light source with a wavelength of infrared or green light and a power of 100W-500W.

9. The laser melting powder metal 3D printing method according to claim 1 or 2, characterized in that: The printing parameters used to control the printing of each layer include laser power, laser beam scanning speed, filling spacing, and scanning angle.

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