Low-angle forming method and device applied to laser powder bed melting and medium

Abstract

The invention relates to a low-angle forming method and device applied to laser powder bed melting and a medium, and belongs to the technical field of additive manufacturing. The forming method comprises the following steps that S1, partition parameter identification logic is established, the parameter area of each layer is identified, and the contour range is preferentially identified; s2, identifying a filling range according to the identified contour range; and S3, establishing underlying logic of a software printing scanning path, performing staged scanning sorting on a scanning track, performing scanning path filling, and performing sorting scanning filling on non-scanned areas. According to the low-angle forming method applied to melting of the laser powder bed, the design limitation of 45-degree forming is broken through, and the effect that forming can be achieved without adding any auxiliary support due to low-angle inclination is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a low-angle forming method, equipment and medium applied to laser powder bed melting. Background Art

[0002] During the laser powder bed fusion process, metal powder is rapidly melted and solidified under the action of laser. For parts with overhanging structures, collapse often occurs during the processing and manufacturing process. The reason depends on the arrangement of the components, which mainly includes the geometric shape and processing direction of the components. It is generally believed that the overhang angle of 45° is the critical angle, or the minimum self-supporting angle, that is, when the overhang angle is higher than the critical angle of 45°, the component can be successfully printed by a 3D printer using laser powder bed melting technology; when the overhang angle is lower than the critical angle of 45°, it is generally believed that the component cannot be self-supporting, and the molten metal powder is prone to collapse under its own gravity and capillary action, causing the printed part to deform. Therefore, temporary support is needed to maintain stability, but temporary support materials increase the printing cost, which not only increases the time for material use and construction, but also increases the time for post-processing. Removing temporary support materials is a tedious and troublesome process, and the processing time may even exceed the time required for printing; removing support materials requires traditional processing, grinding and cutting, which will affect the stress distribution of the component and may even cause damage to the strength of the component; in certain specific cases, some support materials (such as grid structures) cannot even be removed. Summary of the invention

[0003] The object of the present invention is to provide a low-angle forming method, equipment and medium for laser powder bed melting, which can solve the technical problems mentioned in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a low-angle forming method applied to laser powder bed melting, comprising the following steps:

[0005] S1, establish the partition parameter recognition logic, identify the parameter area of ​​each layer, and give priority to identifying the contour range;

[0006] S2, identifying the filling range according to the identified contour range;

[0007] S3, establish the underlying logic of the software printing scanning path, sort the scanning trajectory in stages, and fill the scanning path, sorting and scanning the unscanned areas.

[0008] In a preferred embodiment, in S1, the contour range includes a lower surface contour, a main body contour and an upper surface contour.

[0009] In a preferred embodiment, in S2, the area regions of the lower surface, the main body, and the upper surface are identified and determined with respect to the filling range.

[0010] In a preferred embodiment, the lower surface area and the upper surface area are preferentially identified, and the filling range is determined by subtracting the lower surface area and the upper surface area from the filling range, and the remaining area is the main body area.

[0011] In a preferred embodiment, two adjacent area regions overlap.

[0012] In a preferred implementation, in S3, an arithmetic sequence is used to perform scanning sorting on the scanning trajectory in stages.

[0013] In a preferred implementation, the difference value of the arithmetic sequence is set to 3.

[0014] In a preferred embodiment, during the scan sorting process, a counting ignore algorithm is used to process the scanned areas that are re-identified.

[0015] Another aspect of the present invention provides a low-angle forming device for laser powder bed melting, the device comprising:

[0016] Memory: used to store computer programs;

[0017] Processor: used to implement the low-angle forming method applied to laser powder bed melting as described in any of the above items when executing the computer program.

[0018] On the other hand, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any of the above-mentioned low-angle forming methods applied to laser powder bed melting are implemented.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the low-angle forming method applied to laser powder bed melting provided by the present invention establishes a partition parameter recognition logic, identifies the parameter area of ​​each layer, prioritizes the identification of the contour range, and performs partial area fusion enhancement for each parameter partition; establishes the underlying logic of the software printing scanning path, performs a first scan sorting on the scanning trajectory, performs a second scan sorting on the unscanned area, and finally scans and fills the unscanned area. The present invention can realize low-angle forming and achieve the effect of forming at low angle inclination without adding any auxiliary support. Its advantages are at least reflected in the following three aspects:

[0020] 1. Improve design freedom: It can directly form some overhanging structures, low-angle geometric structures, sharper component edges, and larger diameter internal flow channel structures, greatly improving the manufacturing freedom. Some structures do not require support, and users have more choices in the placement of parts, further liberating the productivity of the equipment.

[0021] 2. Production cost: Since there is no need to add support structures, SLM support-free technology reduces the amount of powder used, thereby reducing material costs. At the same time, it also shortens printing time and reduces post-processing workload, further reducing overall manufacturing costs and improving production efficiency during the printing process and post-processing.

[0022] 3. Part surface quality: The surface quality of the part and the roughness of the lower surface are optimized. The molding space occupied by the support structure is eliminated, and the traces or damage that may be left after the support structure is removed are avoided, thereby improving the overall quality of the part. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a layered schematic diagram of the oblique block in an embodiment of the present invention;

[0024] Figure 2 A diagram showing the division of the fifth layer area of ​​the oblique block in an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of lower surface contour recognition in an embodiment of the present invention;

[0026] Figure 4 It is a structural block diagram of a low-angle forming device applied to laser powder bed melting in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] This embodiment discloses a low-angle forming method for laser powder bed melting, comprising the following steps:

[0030] S1, establish the partition parameter recognition logic, identify the parameter area of ​​each layer, and give priority to identifying the contour range;

[0031] S2, identifying the filling range according to the identified contour range;

[0032] S3, establish the underlying logic of the software printing scanning path, sort the scanning trajectory in stages, and fill the scanning path, sorting and scanning the unscanned areas.

[0033] Specifically, in S1, the contour range includes a lower surface contour, a main body contour and an upper surface contour.

[0034] In S2, the filling range is scaled by a predetermined value according to the gap value set between the outline and the filling.

[0035] The area of ​​the lower surface, main body and upper surface is identified and determined for the filling range, with the lower surface area and the upper surface area being identified first. The filling range is determined by subtracting the lower surface area and the upper surface area from the filling range, and the remaining area is the main body area.

[0036] In the area division of the lower surface, main body and upper surface, two adjacent area areas are overlapped a small amount and regional fusion enhancement is performed to stabilize each parameter area.

[0037] In S3, an arithmetic sorting sequence is used to scan and sort the scanning trajectory in stages. During the sorting process, if the scanned area is recognized again, a counting ignore algorithm will be performed. Finally, the unscanned area will be sorted and scanned to fill in.

[0038] The present invention is further described in detail below in conjunction with the embodiments. It should also be understood that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the present invention all belong to the scope of protection of the present invention.

[0039] In this embodiment, the printed model is a slanted block 1 inclined at 10°. Figure 1 As shown, the inclined block 1 is first layered. According to the specifications of the inclined block 1, it is divided into eight layers, which are composed of a first layer 3, a second layer 4, a third layer 5, a fourth layer 6, a fifth layer 7, a sixth layer 8, a seventh layer 9, and an eighth layer 10. The thickness A of each layer is set to 1 mm.

[0040] The following takes the fifth layer 7 as an example, and combines Figure 2 and Figure 3 The molding method is described in detail, and the molding method specifically comprises the following steps:

[0041] S1, establish partition parameter recognition logic: identify the parameter area of ​​the fifth layer 7, and prioritize the contour range;

[0042] Specifically, the fifth layer 7 is divided into plane parameter areas for display, and the contour range is preferentially identified, that is, the lower surface contour 28 , the first main body contour 19 , the second main body contour 38 , and the upper surface contour 47 are preferentially identified.

[0043] S2, identify the filling range according to the identified contour range: prioritize the lower surface area areas 21, 22, 23, 24, 25, 26, 27, 29; identify the upper surface area areas 40, 41, 42, 43, 44, 45, 46, 11; and finally identify the main body area areas 12, 13, 14, 15, 16, 17, 18, 20, 31, 32, 33, 34, 35, 36, 37.

[0044] S3, establish the underlying logic of the software printing scanning path, perform scanning sorting on the scanning track in stages, and perform scanning path filling, and sort and scan and fill the unscanned areas;

[0045] Specifically, the scanning path is filled according to the set arithmetic sequence and the order of scanning areas:

[0046] The first step is to fill the scanning path of the lower surface area regions 21, 22, 23, 24, 25, 26, 27, and 29. According to the scanning sequence sorting method, the lower surface area region 21, the lower surface area region 24, and the lower surface area region 27 are scanned first; the lower surface area region 22, the lower surface area region 25, and the lower surface area region 29 are scanned secondly; and the lower surface area region 23 and the lower surface area region 26 are scanned lastly.

[0047] The second step is to fill the scanning path of main area areas 12, 13, 14, 15, 16, 17, 18, 20, 31, 32, 33, 34, 35, 36, and 37. According to the scanning sequence sorting method, main area area 12, main area area 15, main area area 18, main area area 32, and main area area 35 are scanned first; main area area 13, main area area 16, main area area 20, main area area 33, and main area area 36 are scanned secondly; main area area 14, main area area 17, main area area 31, main area area 34, and main area area 37 are scanned finally.

[0048] The main body area and the lower surface area will partially overlap 30, which will provide a certain support to the lower surface;

[0049] The third step is to fill the scanning path of the upper surface area regions 40, 41, 42, 43, 44, 45, 46, and 11. According to the scanning sequence sorting method, the upper surface area region 11, the upper surface area region 44, and the upper surface area region 41 are scanned first; the upper surface area region 46, the upper surface area region 43, and the upper surface area region 40 are scanned secondly; and the upper surface area region 45 and the upper surface area region 42 are scanned lastly.

[0050] The main body area and the upper surface area will partially overlap 39;

[0051] Finally, the lower surface contour 28 , the first main body contour 19 , the second main body contour 38 , and the upper surface contour 47 are scanned to complete the scanning process of the fifth layer 7 .

[0052] In S1, the specific method of contour range recognition is:

[0053] Set the printing layer thickness A to 1mm, when the horizontal suspension angle B of the second layer is 50°, and the vertical angle C is 40°, then the length D is obtained according to the formula D=A×tan(C), and the second layer will be about 0.8mm longer than the first layer. When the second layer length D is compared with the layer thickness A, D<A, then the lower surface will not be determined and the lower surface parameters will not be quoted.

[0054] When the horizontal hanging angle B of the third layer is 40°, and the vertical angle C is 50°, then the length D is obtained according to the formula D=A×tan(C), and the third layer will be about 1.2mm longer than the second layer. The length D of the third layer is compared with the layer thickness A. If D>A, it is determined to be the lower surface, and the lower surface width dimension E, that is, the identification range of the lower surface is DA=0.2mm. According to the principle of lever, in order to balance the lever, the two moments (the product of force and lever arm) acting on the lever must be equal. That is: power×power arm=resistance×resistance arm, which can be expressed in algebraic form as F1·l1=F2·l2. Set the power and resistance values ​​to be the same, replace the power and resistance with the overlap width dimension F and the lower surface width dimension E, and the algebraic form will become: overlap width dimension F=lower surface width dimension E. Overlap width dimension F=E=0.2mm.

[0055] When the horizontal hanging angle B of the fourth layer is 30°, and the vertical angle C is 60°, then the length D is obtained according to the formula D=A×tan(C), and the fourth layer will be about 1.7mm longer than the third layer. The length D of the fourth layer is compared with the layer thickness A. If D>A, it is determined to be the lower surface, and the lower surface width dimension E is DA=0.7mm. According to the principle of lever, in order to balance the lever, the two moments (the product of force and lever arm) acting on the lever must be equal. That is: power×power arm=resistance×resistance arm, which can be expressed in algebraic form as F1·l1=F2·l2. Set the power and resistance values ​​to be the same, replace the power and resistance with the overlap width dimension F and the lower surface width dimension E, and the algebraic form will become: overlap width dimension F=lower surface width dimension E. Overlap width dimension F=E=0.7mm.

[0056] In S3, the basis for using the arithmetic sequence is:

[0057] After the lower surface area is identified, the area of ​​each lower surface area of ​​each layer is first sorted and scanned in the form of natural number sequence. Figure 3 As shown, the scanning sequence will be 21, 22, 23, 24, 25, 26, 27, 29. Fix the infrared thermal imager outside the molding cylinder window, and let the optical axis of the thermal imager lens point at the lower surface area during printing. The thermal imager lens is 10 cm away from the molding bar window, and adjust the focal length to make the molding area image clear. Track the laser scanning process of each lower surface area, and collect the temperature rise and cooling data of the melting on the powder bed during laser printing. In order to reduce the error of the measured data, multiple and multiple groups of measurements are performed. The result is that it takes about 3 seconds for the temperature of each lower surface area to rise and fall after printing. The powder melts and solidifies quickly during printing, which will cause the temperature to rise and fall during printing. If the scanning continues without cooling, it will cause the heat energy to concentrate and the local temperature to be too high, which may cause printing failure.

[0058] According to the collected data, the scanning logic is modified to an arithmetic sequence. If the difference is set to 2, the cooling time is too short, which will lead to the problem of heat energy concentration. If the difference is set to 4 or above, the calculation amount of the sorting algorithm will increase. The larger the difference setting value, the more calculation amount of the sorting algorithm will be. Therefore, in this embodiment, the difference is set to 3, and the scanning sequence basis is set to 1, 4, 7, 10, 13, 16. Set the n value as the arrangement order, and the arithmetic sequence process is n = 3n-2. Figure 3 As shown, the scanning order would be to first scan lower surface area region 21, lower surface area region 24, and lower surface area region 27.

[0059] The first sorting is completed, but the lower surface area has not been scanned completely, and there are still 22, 23, 25, 26, and 29 lower surface areas.

[0060] When the second sorting starts, the counting will start again, but the first lower surface area 21 has been scanned. If it is calculated again, it will be scanned again. Using the counting ignore algorithm, the lower surface area where the first sorting is completed is excluded from the second sorting calculation, but it occupies the corresponding position information. The second sorting will start from the natural number sequence 2 for sorting calculation. Figure 3 As shown, the scanning order would be to first scan lower surface area region 22, lower surface area region 25, and lower surface area region 29.

[0061] The third sorting starts, based on the arithmetic sorting sequence and counting ignore algorithm, according to Figure 3 As shown, the scanning order is to first scan the lower surface area 23, and then the lower surface area 26. The path scanning planning of the lower surface is completed.

[0062] Another aspect of the present invention provides a low-angle forming device for laser powder bed melting, Figure 4 The device may include one or more of the following components: a memory, a processor, and one or more computer programs, wherein the one or more computer programs may be stored in the memory and configured to be executed by the one or more processors, and the one or more computer programs are configured to execute the aforementioned low-angle forming method applied to laser powder bed fusion.

[0063] The memory may include a random access memory (RAM) or a read-only memory (ROM). The memory may be used to store instructions, programs, codes, code sets or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for implementing at least one function, instructions for implementing the aforementioned various method embodiments, etc.

[0064] The processor may include one or more processing cores. The processor uses various interfaces and lines to connect the various parts of the entire device, and executes various functions of the device and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory, and calling data stored in the memory. Optionally, the processor can be implemented in at least one hardware form of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor can integrate one or a combination of a central processing unit (CPU) and a modem. Among them, the CPU mainly processes the operating system and application programs; the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor, but may be implemented separately through a communication chip.

[0065] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, a method for SLM unsupported forming parts introduced in any of the above-mentioned embodiments of the invention is implemented. The rest of the content can refer to the prior art and will not be described in detail here.

[0066] Professionals may further appreciate that the various steps described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0067] The low-angle forming method for laser powder bed melting provided by the present invention provides a new scanning recognition and planning idea. It divides and plans the path for each scanning area, and uses an arithmetic sequence method to separate two adjacent area areas by arithmetic sorting. The overlapping part of the lower surface area and the main body area supports the lower surface area according to different angles, thereby ensuring low-angle forming. The present invention breaks through the design limitation of 45° forming and achieves the effect of forming at a low angle without adding any auxiliary support.

[0068] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low-angle forming method for laser powder bed fusion, characterized in that: The following steps are involved: S1, establish the partition parameter recognition logic, identify the parameter area of ​​each layer, and give priority to identifying the contour range; S2, identifying the filling range according to the identified contour range; S3, establish the underlying logic of the software printing scanning path, sort the scanning trajectory in stages, and fill the scanning path, sorting and scanning the unscanned areas.

2. The low-angle forming method for laser powder bed fusion according to claim 1, characterized in that: In S1, the contour range includes a lower surface contour, a main body contour and an upper surface contour.

3. The low-angle forming method for laser powder bed melting according to claim 2, characterized in that: In S2, the area region recognition and determination of the lower surface, the main body, and the upper surface are performed for the filling range.

4. The low-angle forming method for laser powder bed melting according to claim 3 is characterized in that: The lower surface area and the upper surface area are identified preferentially, and the filling range is determined by subtracting the lower surface area and the upper surface area from the filling range, and the remaining area is the main body area.

5. The low-angle forming method for laser powder bed fusion according to claim 4, characterized in that: Two adjacent area regions overlap.

6. The low-angle forming method for laser powder bed fusion according to claim 1, characterized in that: In S3, an arithmetic sorting sequence is used to sort the scanning trajectory in stages.

7. The low-angle forming method for laser powder bed fusion according to claim 6, characterized in that: The difference value of the arithmetic sequence is set to 3.

8. The low-angle forming method for laser powder bed fusion according to claim 1, characterized in that: During the scan sorting process, a counting ignore algorithm is used to process the scanned areas that are re-identified.

9. A low-angle forming device for laser powder bed melting, characterized in that: The device comprises: Memory: used to store computer programs; Processor: used to implement the low-angle forming method applied to laser powder bed melting as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the low-angle forming method applied to laser powder bed melting as claimed in any one of claims 1 to 7.

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