A powder bed additive manufacturing grafting printing clamping and positioning method

Abstract

The present invention relates to the field of additive manufacturing technology, and specifically to a powder bed additive manufacturing grafting printing clamping and positioning method, comprising: step 1, fixing a processing substrate on a lifting part of a forming platform; a reference part is also provided on the forming platform, the reference part includes a horizontally arranged forming plane, and a reference coordinate system is provided on the forming plane, which is recorded as a forming coordinate system; step 2, adjusting the height of the lifting part so that the top surface of the processing substrate and the forming plane are at the same height; step 3, using a camera installed on the top of the additive manufacturing equipment to shoot an image to be processed, and the content of the image to be processed includes the top surface of the processing substrate; step 4, calculating the position information of the top surface contour of the processing substrate in the forming coordinate system; step 5: importing the top surface contour of the processing substrate and its position information in the forming coordinate system into a slicing software. This method can ensure the precise positioning of the additive manufacturing part model when the additive manufacturing grafting printing is based on powder bed fusion forming.

Description

Technical Field

[0001] The invention relates to the technical field of additive manufacturing, and in particular to a powder bed additive manufacturing grafting printing clamping and positioning method. Background Art

[0002] Additive Manufacturing (AM), commonly known as 3D printing, is an emerging advanced manufacturing technology with the advantages of high degree of digitization and the ability to form complex spatial structures. It integrates computer-aided design, material processing and molding technology, and is based on digital model files. It uses software and CNC systems to stack special metal materials, non-metal materials and medical biomaterials layer by layer in the form of extrusion, sintering, melting, light curing, spraying, etc. to produce physical objects.

[0003] Powder bed fusion forming additive manufacturing is an important process in additive manufacturing technology, mainly including laser selective melting forming and electron beam selective melting forming, which has important application value in the medical and health, aerospace, tool and mold industries. However, due to the slow forming speed of powder bed fusion forming additive manufacturing, the forming efficiency of this process is still low; at the same time, because its raw material is powder, the cost is high. Efficiency and cost issues have seriously hindered the promotion and application of this process.

[0004] In order to alleviate the efficiency and cost problems, some technicians have proposed a grafting printing technology based on the powder bed fusion forming additive manufacturing process. This technology divides the parts to be processed into two parts, one of which does not have a complex internal structure as a processing base, and the other part has a complex internal structure (such as an accompanying cooling channel); the processing base is processed by traditional turning, milling, planing and grinding. Since this part has no complex internal structure, it can be processed quickly and economically; and the part with a complex internal structure is processed and manufactured on the top surface of the processing base using the powder bed fusion forming additive manufacturing process. In this way, the ability of additive manufacturing to form complex spatial structures can be fully utilized.

[0005] If the above-mentioned grafting technology can be implemented smoothly, it can not only give full play to the advantages of the powder bed fusion forming additive manufacturing process, but also effectively make up for its shortcomings of low efficiency and high cost, which is undoubtedly of great significance for the promotion and application of this industry. However, in practical applications, there is a serious problem with grafting printing, that is, how to position the model of the additive manufacturing part to ensure that the additive manufacturing part has an accurate relative position relationship with the machined substrate, so that the final manufactured part has the correct geometric structure. If the positioning of the model of the additive manufacturing part is not accurate enough, that is, the bottom surface of the grafted printed part does not completely overlap with the top surface of the machined substrate, even if there is only a small error, the misalignment of the two parts will cause the formed workpiece to fail to meet the quality requirements and cannot be put into industrial use.

[0006] Therefore, how to ensure the precise positioning of the additive manufacturing part model during additive manufacturing grafting printing based on powder bed fusion molding has become a key issue at present. Summary of the invention

[0007] In view of the shortcomings of the above-mentioned prior art, the present invention provides a powder bed additive manufacturing grafting printing clamping and positioning method, which can ensure the precise positioning of the additive manufacturing part model during the additive manufacturing grafting printing based on powder bed fusion forming, so that the bottom surface of the grafted printed part is completely overlapped with the top surface of the processing substrate, thereby ensuring the yield rate of the formed workpiece.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A powder bed additive manufacturing grafting printing clamping and positioning method, comprising the following steps:

[0010] Step 1, fixing the processing substrate on the lifting part of the forming platform; the forming platform is also provided with a reference part, the reference part includes a horizontally arranged forming plane, and a forming coordinate system is provided on the forming plane, and the forming coordinate system is a reference coordinate system of the forming plane on the horizontal plane;

[0011] Step 2: Adjust the height of the lifting part so that the top surface of the processing base and the forming plane are at the same height;

[0012] Step 3: using a camera installed on the top of the additive manufacturing equipment to capture the image to be processed, wherein the content of the image to be processed includes the top surface of the processed substrate;

[0013] Step 4, calculating the position information Λ of the top surface profile of the processed substrate in the forming coordinate system;

[0014] Step 5: Import the top surface contour of the processed substrate and its position information Λ in the forming coordinate system into the slicing software; then import the model to be grafted and printed into the slicing software, and extract the bottom surface contour of the model to be printed;

[0015] Step 6: Calculate the rotation angle and translation required to align the bottom surface contour of the model to be printed with the top surface contour of the processed substrate;

[0016] Step 7: After rotating and moving the model to be printed according to the calculation results of step 6, the model to be printed is sliced ​​and printing parameters are set, and then grafting printing is performed.

[0017] Preferably, a plurality of calibration points are provided on the forming plane, the calibration points are not on the same straight line, and the actual distances between the calibration points are pre-calibrated; in step 3, the content of the image to be processed also includes the calibration points.

[0018] Preferably, the number of calibration points is greater than or equal to 3 and less than or equal to 5.

[0019] Preferably, step 4 comprises:

[0020] Step 4.1, according to the actual distance between each calibration point and the pixel distance of each calibration point in the image to be processed, calculate the distance between the pixels in the image to be processed and record it as the pixel spacing L;

[0021] Step 4.2: establish a calibration coordinate system based on the relative positions of the calibration points. The calibration coordinate system is in the plane where the calibration points are located, and the calibration coordinate system is rotated by an angle α and translated by an amount [x b y b ] T After translation, it coincides with the forming coordinate system; where α represents the angle of counterclockwise rotation, x b ,y b They respectively represent the movement amounts along the x-axis and y-axis directions of the forming coordinate system after the coordinate system is rotated;

[0022] Step 4.3, according to the relative position relationship between the top surface contour of the processed substrate and the calibration point in the image to be processed, and the pixel spacing L of the image to be processed, calculate the position information Γ of the top surface contour of the processed substrate in the calibration coordinate system, and obtain the specific coordinates of each point of the top surface contour of the processed substrate in the calibration coordinate system; then calculate the position information Λ of the top surface contour of the processed substrate in the forming coordinate system by the following formula:

[0023] Preferably, step 6 comprises:

[0024] Step 6.1, in the slicing software, capture an image including the top surface contour of the processed substrate and the bottom surface contour of the model to be printed, and record it as an analysis image;

[0025] Step 6.2, calculating and analyzing the actual distance L1 between adjacent pixels in the image;

[0026] Step 6.3, calculate and analyze the centroid coordinates (x jd ,y jd ) and direction angle β jd , and the centroid coordinates of the bottom contour of the model to be printed (x mod ,y mod ) and direction angle β mod ;

[0027] Step 6.4, calculate the counterclockwise rotation required to align the ground contour of the model to be printed with the top contour of the processing base [0 0 β jd -β mod ] T or [0 0 β jd -β mod +π] T , and the movement amount [L1(x jd -x mod ) L1(y jd -y mod ) 0] T ;

[0028] In step 7, when rotating the bottom surface contour of the model to be printed, first select one of the counterclockwise rotation amounts in 6.4 for rotation. If the bottom surface contour to be printed after rotation is inconsistent with the top surface contour of the processed substrate, select another counterclockwise rotation amount for re-rotation.

[0029] Preferably, in step 6.2, the actual distance L1 between adjacent pixels in the analysis image is calculated based on the position information Λ of the top surface contour of the processed substrate in the forming coordinate system and the pixels of the top surface contour of the processed substrate in the analysis image.

[0030] Preferably, in step 6.3, the centroid coordinates (x jd ,y jd ):

[0031] x jd =mt i / mt0;y jd =mt j / mt0; where M and N represent image pixels, and p(i,j) represents the information of the analyzed image at the pixel point (i,j). Its values ​​are as follows:

[0032]

[0033] The centroid coordinates (x mod ,y mod ):

[0034] x mod =mt' t / mt'0,y mod =mt' j / mt'0; where M and N represent image pixels, and q(i,j) represents the information of Θ at the pixel point (i,j) in the analyzed image, and its values ​​are as follows:

[0035]

[0036] Preferably, in step 6.3, the direction angle β of the top surface contour of the processed substrate in the analysis image is calculated according to the following formula: jd :

[0037]

[0038] Where a=(mt i2 -mt j2 ) / mt0-x jd 2 +y jd 2 , b=2(mt i / mt0-x jd ·y jd ),

[0039] The direction angle β of the bottom surface contour of the model to be printed in the image is calculated according to the following formula: mod :

[0040]

[0041] Where a'=(mt' i2 -mt' j2 ) / mt0-(x mod ) 2 +(y mod ) 2 , b'=2(mt' i / mt'0-x mod ·y mod ),

[0042] Preferably, in step 1, an electromagnetic chuck is provided on the lifting portion of the forming platform, and the processing substrate is placed on the electromagnetic chuck.

[0043] Preferably, before executing step 1, step 0 is also included, which is to check whether the top surface contour of the processing substrate to be machined is an axisymmetric figure or a centrally symmetrical image. If so, it is designed to be an asymmetric shape before processing.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This method cleverly sets up multiple reference systems and conversion methods. Through the actual distance of the calibration points, the conversion of each coordinate system and the analysis and processing of the pixel spacing on each image, the model to be printed can be rotated and translated before grafting printing to ensure that the bottom surface of the model to be printed completely overlaps with the top surface of the processed substrate during printing, thereby ensuring the yield rate of the formed workpiece.

[0046] Moreover, in actual operation, it is only necessary to store the actual distance of each calibration point in the processing module in advance. After that, the calibration points, calibration coordinate system, conversion between the forming coordinate system, and pixel spacing analysis on each graphic can all be calculated automatically by the processor. The staff only needs to place the processing substrate. The operation is simple and the degree of automation is high, which can ensure the efficiency of grafting printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to make the purpose, technical solution and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0048] Figure 1 is a flow chart in an embodiment;

[0049] Figure 2 This is a schematic diagram of the structure in which the processing substrate is placed on the forming platform in the embodiment;

[0050] Figure 3 Schematic diagram of the position of the top surface contour of the processed substrate in the forming coordinate system in the embodiment.

[0051] The reference numerals in the drawings of the specification include: a lifting part 1, an electromagnetic suction cup 2, a processing base 3, a model to be printed 4, a calibration point 5, a forming plane 6, a forming coordinate system 7, and a calibration coordinate system 8. DETAILED DESCRIPTION

[0052] The following is a further detailed description through specific implementation methods:

[0053] In order to solve the above problems, the present invention provides a powder bed additive manufacturing grafting printing clamping and positioning method, which can rotate and translate the model 4 to be printed before grafting printing to ensure that the bottom surface of the model 4 to be printed completely overlaps with the top surface of the processing substrate 3 during the specific printing, thereby ensuring the yield rate of the formed workpiece. In addition, the analysis and processing processes involved in the calculation process of this application can all be calculated by the automatic operation of the processor. The staff only needs to place the processing substrate 3, which is simple to operate and has a high degree of automation, and can ensure the efficiency of grafting printing.

[0054] Example:

[0055] like Figure 1 As shown, this embodiment discloses a powder bed additive manufacturing grafting printing clamping and positioning method, including the following steps:

[0056] Step 1: fix the processing substrate 3 on the lifting part 1 of the forming platform; specifically, Figure 2 As shown, an electromagnetic chuck 2 is placed on the lifting seat of the forming platform, and the processing substrate 3 is placed on the electromagnetic chuck 2. Since most of the processing substrate 3 is ferromagnetic materials such as iron-based and nickel-based, it can be fixed by the magnetic force generated by the electromagnetic chuck 2 after it is energized. Compared with other fixing methods, the operation is simpler. Figure 3 As shown, a reference part is also provided on the forming platform, and the reference part includes a horizontally arranged forming plane 6, on which a reference coordinate system is provided, which is recorded as a forming coordinate system 7. In this embodiment, the forming plane 6 is distributed on both sides of the lifting part 1.

[0057] A plurality of calibration points 5 are provided on the forming plane 6, and the calibration points 5 are not on the same straight line, and the actual distances between the calibration points 5 have been pre-calibrated; the calibration points 5 may be circular or square holes or bosses, and the number of the calibration points 5 is greater than or equal to 3 and less than or equal to 5. In this embodiment, the calibration points 5 are circular bosses, and the number of the calibration points 5 is 3, i.e. Figure 3 Point A, point B and point C in the diagram.

[0058] Step 2: Adjust the height of the lifting part 1 so that the top surface of the processed substrate 3 is at the same height as the forming plane 6. In specific operation, the height position of the bottom surface of the processed substrate 3 can be measured by infrared ranging equipment, and a reminder is issued when it moves to a suitable position.

[0059] Step 3: Use a camera installed on the top of the additive manufacturing equipment to capture the image to be processed, where the content of the image to be processed includes the top surface of the processed substrate 3 and each calibration point 5.

[0060] Step 4: Calculate the position information of the top surface profile of the processed substrate 3 in the forming coordinate system 7; Specifically, step 4 includes:

[0061] Step 4.1, according to the actual distance between the calibration points 5 and the pixel distance of the calibration points 5 in the image to be processed, the distance between the pixels in the image to be processed is calculated and recorded as the pixel spacing L. For ease of understanding, the two calibration points A and B are taken as an example for explanation. The actual distance between the two calibration points A and B is assumed to be H, and the pixel distance between the two calibration points A and B is h. Then, the actual distance between adjacent pixels on the image to be processed, that is, the pixel spacing L = H / h.

[0062] Step 4.2, establish a calibration coordinate system 8 based on the relative positions of the calibration points 5. Specifically, in the plane determined by the calibration points A, B, and C, the calibration point C is taken as the origin of the coordinates, CA is taken as the y-axis, and the x-axis is further determined based on the right-hand rule. The calibration coordinate system 8 is rotated by an angle α and translated by an amount [x b y b ] T After translation, it coincides with the forming coordinate system 7; where α represents the angle of counterclockwise rotation, x b ,y b They respectively represent the movement amounts along the x-axis direction and the y-axis direction of the forming coordinate system 7 after the coordinate system is rotated.

[0063] Step 4.3, according to the relative position relationship between the top surface contour of the processed substrate 3 in the image to be processed and the calibration point 5, and the pixel spacing L of the image to be processed, calculate the position information Γ of the top surface contour of the processed substrate 3 in the calibration coordinate system 8, that is, the specific coordinates of each point of the top surface contour of the processed substrate 3 in the calibration coordinate system 8. Then calculate the position information Λ of the top surface contour of the processed substrate 3 in the forming coordinate system 7 by the following formula:

[0064] Step 5: Import the top surface contour of the processed substrate 3 and its position information Λ in the forming coordinate system 7 into the slicing software; then import the model 4 to be printed to be grafted into the slicing software, and extract the bottom surface contour of the model 4 to be printed. The slicing software can directly select the existing 3D printing slicing software (such as cura, s3d, etc.), which will not be repeated here.

[0065] Step 6: Calculate the rotation angle and translation required to align the bottom surface contour of the to-be-printed model 4 with the top surface contour of the processed substrate 3. Specifically, step 6 includes:

[0066] Step 6.1, in the slicing software, intercept an image including the top surface profile Λ of the processed substrate 3 and the bottom surface profile Θ of the model to be printed 4, and record it as an analysis image;

[0067] Step 6.2, calculate the actual distance L1 between adjacent pixel points in the analysis image; specifically, based on the position information Λ of the top surface contour of the processed substrate 3 in the forming coordinate system 7, and the pixels of the top surface contour of the processed substrate 3 in the analysis image, calculate the actual distance L1 between adjacent pixel points in the analysis image.

[0068] Step 6.3, calculate and analyze the centroid coordinates (x jd ,y jd ) and direction angle β jd , and the centroid coordinates (x mod ,y mod ) and direction angle βmod ;

[0069] In specific implementation, the centroid coordinates (x jd ,y jd ):

[0070] x jd =mt i / mt0,y jd =mt j / mt0; where M and N represent image pixels, and p(i,j) represents the information of Λ at the pixel point (i,j) in the analyzed image, and its value is as follows:

[0071]

[0072] The bottom contour of the model 4 to be printed is recorded as θ, and the same method is used to calculate the centroid coordinates (x mod ,y mod ), as follows:

[0073] x mod =mt' t / mt'0,y mod =mt' j / mt'0; where M and N represent image pixels, and q(i,j) represents the information of Θ at the pixel point (i,j) in the analyzed image, and its values ​​are as follows:

[0074]

[0075] The direction angle β of the top surface profile of the processing substrate 3 is calculated according to the following formula jd :

[0076]

[0077] Where a=(mt i2 -mt j2 ) / mt0-(x jd ) 2 +(y jd ) 2 , b=2(mt i / mt0-x jd ·y jd ),

[0078] The same method is used to calculate the direction angle β of the bottom surface contour of the model 4 to be printed in the analysis image. mod , as follows:

[0079]

[0080] Where a′=(mt′ i2 -mt′ j2 ) / mt0-(x mod ) 2 +(y mod ) 2 , b'=2(mt' i / mt'0-x mod ·y mod ),

[0081] Step 6.4, calculate the counterclockwise rotation required to align the ground contour of the model 4 to be printed with the top contour of the processing base 3 [0 0 β jd -β mod ] T or [0 0 β jd -β mod +π] T , and the movement amount [L1(x jd -x mod ) L1(y jd -y mod ) 0] T .

[0082] Step 7, after rotating and moving the model 4 to be printed according to the calculation results of step 6, the model 4 to be printed is sliced ​​and the printing parameters are set, and then the grafting printing is performed. When rotating the bottom surface contour of the model 4 to be printed, first select a counterclockwise rotation amount to rotate. If the bottom surface contour to be printed after rotation is inconsistent with the top surface contour of the processed substrate 3, another counterclockwise rotation amount is selected to rotate again. In this way, grafting printing is performed on the top surface of the processed substrate 3, which can ensure that the bottom surface of the model 4 to be printed completely overlaps with the top surface of the processed substrate 3, thereby ensuring the quality of the processed product.

[0083] In specific implementation, before executing step 1, step 0 may also be included to check whether the top surface profile of the processing substrate to be machined is an axisymmetric figure or a centrally symmetrical image. If so, it is designed to be an asymmetric shape before processing, for example, a rectangular protrusion is added to the surface. In this way, the uniqueness of the calculation results in the subsequent operation process can be guaranteed.

[0084] By using this method, through the actual distance of the calibration point 5, the conversion of several coordinate systems and the analysis and processing of several pixel spacings, the model to be printed 4 can be rotated and translated before grafting printing to ensure that during the specific printing, the bottom surface of the model to be printed 4 completely overlaps with the top surface of the processing substrate 3, thereby ensuring the yield rate of the formed workpiece.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A powder bed additive manufacturing grafting printing clamping and positioning method, characterized in that: The following steps are involved: Step 1, fixing the processing substrate on the lifting part of the forming platform; the forming platform is also provided with a reference part, the reference part includes a horizontally arranged forming plane, and a forming coordinate system is provided on the forming plane, and the forming coordinate system is a reference coordinate system of the forming plane on the horizontal plane; Step 2: Adjust the height of the lifting part so that the top surface of the processing base and the forming plane are at the same height; Step 3: using a camera installed on the top of the additive manufacturing equipment to capture the image to be processed, wherein the content of the image to be processed includes the top surface of the processed substrate; Step 4, calculating the position information Λ of the top surface profile of the processed substrate in the forming coordinate system; Step 5: Import the top surface contour of the processed substrate and its position information Λ in the forming coordinate system into the slicing software; then import the model to be grafted and printed into the slicing software, and extract the bottom surface contour of the model to be printed; Step 6: Calculate the rotation angle and translation required to align the bottom surface contour of the model to be printed with the top surface contour of the processed substrate; Step 7: After rotating and moving the model to be printed according to the calculation results of step 6, the model to be printed is sliced ​​and printing parameters are set, and then grafting printing is performed.

2. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 1, characterized in that: A plurality of calibration points are arranged on the forming plane, the calibration points are not on the same straight line, and the actual distances between the calibration points are pre-calibrated; in step 3, the content of the image to be processed also includes the calibration points.

3. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 2, characterized in that: The number of calibration points is greater than or equal to 3 and less than or equal to 5.

4. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 2, characterized in that: Step 4 includes: Step 4.1, according to the actual distance between each calibration point and the pixel distance of each calibration point in the image to be processed, calculate the distance between the pixels in the image to be processed and record it as the pixel spacing L; Step 4.2: establish a calibration coordinate system based on the relative positions of the calibration points. The calibration coordinate system is in the plane where the calibration points are located, and the calibration coordinate system is rotated by an angle α and translated by an amount [x b y b ] T After translation, it coincides with the forming coordinate system; where α represents the angle of counterclockwise rotation, x b ,y b They respectively represent the movement amounts along the x-axis and y-axis directions of the forming coordinate system after the coordinate system is rotated; Step 4.3, according to the relative position relationship between the top surface contour of the processed substrate and the calibration point in the image to be processed, and the pixel spacing L of the image to be processed, calculate the position information Γ of the top surface contour of the processed substrate in the calibration coordinate system, and obtain the specific coordinates of each point of the top surface contour of the processed substrate in the calibration coordinate system; then calculate the position information Λ of the top surface contour of the processed substrate in the forming coordinate system by the following formula:

5. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 4, characterized in that: Step 6 includes: Step 6.1, in the slicing software, capture an image including the top surface contour of the processed substrate and the bottom surface contour of the model to be printed, and record it as an analysis image; Step 6.2, calculating and analyzing the actual distance L1 between adjacent pixels in the image; Step 6.3, calculate and analyze the centroid coordinates (x jd ,y jd ) and direction angle β jd , and the centroid coordinates of the bottom contour of the model to be printed (x mod ,y mod ) and direction angle β mod ; Step 6.4, calculate the counterclockwise rotation required to align the ground contour of the model to be printed with the top contour of the processing base [0 0 β jd -β mod ] T or [0 0 β jd -β mod +π] T , and the movement amount [L1(x jd -x mod ) L1(y jd -y mod ) 0] T ; In step 7, when rotating the bottom surface contour of the model to be printed, first select one of the counterclockwise rotation amounts in 6.4 for rotation. If the bottom surface contour to be printed after rotation is inconsistent with the top surface contour of the processed substrate, select another counterclockwise rotation amount for re-rotation.

6. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 5, characterized in that: In step 6.2, the actual distance L1 between adjacent pixel points in the analysis image is calculated based on the position information Λ of the top surface contour of the processed substrate in the forming coordinate system and the pixels of the top surface contour of the processed substrate in the analysis image.

7. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 6, characterized in that: In step 6.3, the centroid coordinates (x jd ,y jd ): x jd =mt i / mt0;y jd =mt j / mt0; where M and N represent image pixels, and p(i,j) represents the information of the analyzed image at the pixel point (i,j). Its values ​​are as follows: The bottom contour of the model to be printed is recorded as θ, and the centroid coordinates (x mod ,y mod ): x mod =mt′ t / mt′0,y mod =mt′ j / mt′0; where M and N represent image pixels, and q(i,j) represents the information of Θ at the pixel point (i,j) in the analyzed image, and its values ​​are as follows:

8. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 7, characterized in that: In step 6.3, the direction angle β of the top surface contour of the processed substrate in the analysis image is calculated according to the following formula: jd : where a = (mt i2 - mt j2 ) / mt0 - x jd 2 + y jd 2 , b = 2(mt i / mt0 - x jd ·y jd ), The direction angle β of the bottom surface contour of the model to be printed in the image is calculated according to the following formula: mod : where a' = (mt′ i2 -mt′ j2 ) / mt0 - (x mod ) 2 + (y mod ) 2 , b' = 2(mt′ i / mt′0 - x mod ·y mod ), 9. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 8, characterized in that: In step 1, an electromagnetic chuck is provided on the lifting part of the forming platform, and the processing substrate is placed on the electromagnetic chuck.

10. The powder bed additive manufacturing grafting printing clamping and positioning method according to claim 9, characterized in that: Before executing step 1, step 0 is also included, which is to check whether the top surface contour of the processing substrate to be machined is an axisymmetric figure or a centrally symmetrical image. If so, it is designed to be an asymmetric shape before processing.

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