TW201632343A - Self-adaptive method of tuning printing direction in printing three-dimension model and system to achieve it - Google Patents

Abstract

The present disclosure provides a self-adaptive method of tuning printing direction in printing three-dimension model and system to achieve it. The method includes proceeding gravitational rolling simulation on a three-dimension model before printing the three-dimension model, to ensure a stable placing position of the three-dimension model with least supporting portions under gravity, and then setting the three-dimension model based on the stable placing position, to proceed a slicing simulation on the three-dimension model, to ensure a three-dimension printing direction of the three-dimension model, at the end, adopting the three-dimension printing direction of the three-dimension model to print the three-dimension model.

Description

Three-dimensional model printing method for self-adjusting printing direction and its system System

The present invention relates to three-dimensional printing techniques, and more particularly to a three-dimensional model printing method and system thereof for self-adjusting the printing direction.

Three-dimensional printing is a form of additive manufacturing technology. In additive manufacturing technology, a three-dimensional printing model is created by a three-dimensional printer through a continuous physical layer of output. Compared with other additive manufacturing technologies, 3D printers have the advantages of high speed, low price and high ease of use. The 3D printer is a device that can print real three-dimensional objects. It is functionally the same as the laser forming technology. It uses layered processing and superposition forming, which is to create a three-dimensional printing model by adding materials layer by layer. Traditional material removal techniques are completely different. The so-called three-dimensional printer is based on the technical principle of the inkjet printer, because the process of layered processing is very similar to the working principle of the inkjet printer.

At present, when a three-dimensional printer performs printing of a three-dimensional printing model, firstly, it is necessary to obtain a three-dimensional printing model data of a three-dimensional printing model; Then, according to the three-dimensional printing model data of the three-dimensional printing model, the three-dimensional printing is performed by using the preset universal printing parameter data; finally, the physical finished product produced by the three-dimensional printing model is printed.

In the three-dimensional printing process of a three-dimensional printer, there is a great correlation between the printing direction of the three-dimensional printing and the printing time, the printing consumables and the printing quality. At present, the three-dimensional printing direction of the three-dimensional printing model is preset by the three-dimensional printer, for example, the vertical direction from bottom to top or/and the horizontal direction from left to right, and the printing method is sequentially followed. Print a 3D print model. However, in this way, the direction of the three-dimensional printing is determined, which is preset, and is not set for a three-dimensional printing model structure to be printed, so that the printing quality is lowered. Therefore, in order to print a three-dimensional printing model structure to be printed, it is necessary to manually adjust the three-dimensional printing direction of the three-dimensional printer, so that the disadvantaged user operates the three-dimensional printer and needs cumbersome The process creates difficulties in implementation.

One technical aspect of the present invention relates to a three-dimensional model printing method for self-adjusting the printing direction. The three-dimensional model printing method can adaptively adjust the three-dimensional printing direction of the three-dimensional printer, and the operation is simple, easy to implement, and improved. Print quality. In addition, the present invention also provides a three-dimensional printing system for self-adjusting the printing direction, and the system can adaptively adjust the three-dimensional printing direction of the three-dimensional printer, and the operation is simple, easy to implement, and the printing quality is improved.

According to one or more embodiments of the present invention, a three-dimensional model printing method for self-adjusting the printing direction includes gravity rolling a three-dimensional printing model Dynamic simulation to determine the stable placement of the 3D printing model under the action of gravity with minimal external support; and simulation of the 3D printing model after simulating the placement of the 3D printing model based on the placement of the least external support, Determine the 3D printing orientation of the 3D printing model.

In one or more embodiments of the present invention, the step of obtaining the position of the least external support comprises: setting the static position of the three-dimensional printing model to be the initial position through the gravity rolling simulation; and the three-dimensional printing model from the initial At the beginning of the position, the object is scrolled under simulated gravity conditions, so that the three-dimensional printing model reaches a natural stable stable position; and the three-dimensional space coordinates of the natural stable stable placement position are recorded as the three-dimensional position of the least external support. Spatial coordinates.

In one or more embodiments of the present invention, the step of performing the gravity rolling simulation includes determining the three-dimensional printing model by determining the consistency between the center of gravity of the three-dimensional printing model and the direction of gravity, and combining the features of the three-dimensional printing model with the horizontal plane. Whether it can be kept still at the position and preset the static offset value (Buffer). When the deviation between the center of gravity of the three-dimensional printing model and the gravity direction reaches the preset static deviation value, the three-dimensional image is determined. Print the placement of the model.

In one or more embodiments of the present invention, in the gravity rolling simulation described above, the object scrolling under simulated gravity conditions has a scrolling direction, wherein the selection of the scrolling direction includes the gravity direction of the initial position of the three-dimensional printing model. At the center, the rolling direction is selected by a 360-degree bisector angle around the gravity ground plane, wherein the gravity ground plane is a horizontal plane at which the longitudinal direction where the gravity direction is located and the lateral boundary where the center of gravity of the three-dimensional printing model is located.

In one or more embodiments of the present invention, the step of selecting the scrolling direction by the angle of the 360 degrees around the gravity plane centering on the gravity direction of the initial position of the three-dimensional printing model includes: The 360 degree of the ground plane is divided by the preset number of parts, and the gravity ground plane formed by the equal division forms a plurality of areas, and the plurality of areas respectively have the area direction, and the three-dimensional printing model is parabolically tested in the area direction, in the gravity rolling simulation. After the three-dimensional printing model is naturally stabilized, the three-dimensional space coordinates of the position of the three-dimensional printing model are recorded; after the horizontal translation and the rotation transformation are performed on the three-dimensional space coordinates of the placement position, the positioning position is compared and filtered out. The same position is set, and the position of the three-dimensional printing model is obtained after screening; and the swaying simulation of the position of the three-dimensional printing model after the screening is performed, and the pendulum of the three-dimensional printing model is obtained. The stability of the position is set, and the position with the highest stability is used as a three-dimensional printing model to achieve a stable and stable position.

In one or more embodiments of the present invention, the step of performing the simulated slicing is to perform a simulated slicing on the three-dimensional printing model at the stable placement position, and generate a printing control command in each corresponding slice to print the printing control. The instructions are converted to a graphic code GCode for printing.

In one or more embodiments of the present invention, the three-dimensional model printing method further includes performing projection contour analysis on the three-dimensional printing model to determine the placement position of the three-dimensional printing model before performing the step of simulating the slice. For the external support, the optimal placement position in which the external support is optimal is selected as the determined placement position.

In one or more embodiments of the present invention, the step of performing projection contour analysis on the three-dimensional printing model includes: a) obtaining a three-dimensional printing model At the current angle of the projection map, the contour map is identified by the contour curve; b) the feature position is proposed according to the result of the contour curve recognition, and the spatial position of the three-dimensional printing model corresponding to the feature position is recorded; c) determining whether the spatial position is already in the three-dimensional In the print model, if yes, replace the current angle with the next angle, return to step a); if not, perform step d); d) analyze the outer contour surface features of the 3D printing model, and calculate the corresponding 3D Print the cumulative surface area of the model; e) judge the projection of all angles is completed, if yes, perform step f); if not, replace the current angle with the next angle, return to step a) And f) selecting the placement position corresponding to the smallest of the cumulative surface areas as the optimal placement position for the external support as the placement position determined by the three-dimensional printing model.

According to one or more embodiments of the present invention, a three-dimensional printing system that self-adjusts the printing direction includes a gravity scrolling simulation unit and an analog slicing unit. The gravity rolling simulation unit is used for gravity rolling simulation of the three-dimensional printing model to determine the placement position of the three-dimensional printing model under the action of gravity with the least external support. The simulation slicing unit is configured to simulate placing the three-dimensional printing model according to the determined placement position, and then performing simulation slicing on the three-dimensional printing model to determine the three-dimensional printing direction of the three-dimensional printing model.

In one or more embodiments of the present invention, the three-dimensional printing system further includes a projection contour analyzing unit configured to analyze a projection contour of the three-dimensional printing model to determine a plurality of placement positions of the three-dimensional printing model. For the required external support, the optimal placement position in which the external support is optimal is selected as the determined placement position.

It can be seen from the foregoing solution that an embodiment of the present invention performs gravity scrolling simulation on a three-dimensional printing model before printing a three-dimensional printing model entity, and determines a placement position of the three-dimensional printing model using a minimum external support under the action of gravity; Secondly, after simulating the three-dimensional printing model according to the determined placement position, the three-dimensional printing model is simulated and sliced to determine the three-dimensional printing direction of the three-dimensional printing model; finally, the three-dimensional printing model is determined by using the three-dimensional printing model. Print the direction to print the finished product of the 3D printing model. The system for self-adjusting the three-dimensional printing direction according to an embodiment of the invention is simple in operation, easy to implement, and improves the quality of printing.

101~102‧‧‧Steps

1‧‧‧ Direction

2‧‧‧ Direction

3‧‧‧ Direction

4‧‧‧ Direction

1‧‧‧ position

2‧‧‧ position

3‧‧‧ position

520‧‧‧ Surface

601~609‧‧‧Steps

720‧‧‧Gravity Rolling Simulation Unit

740‧‧‧Projection Profile Analysis Unit

760‧‧‧Simulation slice unit

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; Method flow chart of the method.

FIG. 2 is a schematic diagram showing deviations between the center of gravity and the direction of gravity of the three-dimensional printing model according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a rolling direction of a gravity scroll simulation provided by an embodiment of the present invention.

FIG. 4 is a schematic diagram showing contour projection of a three-dimensional printing model when the projection angle is position 1, 2, and 3 according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing the contour projection of the three-dimensional printing model and the three-dimensional printing model when the positions 1, 2, and 3 shown in FIG. 4 are provided in the embodiment of the present invention.

FIG. 6 is a flowchart of a method for performing projection contour analysis on a three-dimensional printing model according to an embodiment of the present invention.

FIG. 7 is a schematic diagram showing the system structure of a three-dimensional model printing system for self-adjusting the printing direction according to an embodiment of the present invention.

The embodiments of the present invention are disclosed in the following drawings, and the details of However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not necessary. In addition, some of the conventional structures and elements are shown in the drawings in a simplified schematic manner in order to simplify the drawings.

In one embodiment of the present invention, in order to self-adjust the printing direction of the three-dimensional printing, thereby simplifying the operation of the user, and easily implementing and improving the quality of the printing, the printing process of the three-dimensional printing model is simulated, and the three-dimensional printing model is determined. Three-dimensional printing direction. Specifically, before the printing of the three-dimensional printing model entity, the gravity scrolling simulation of the three-dimensional printing model is performed to determine the placement position of the three-dimensional printing model using the least external support under the force of gravity; secondly, according to the determined pendulum After the three-dimensional printing model is placed and placed, the three-dimensional printing model is simulated and sliced to determine the three-dimensional printing direction of the three-dimensional printing model. Finally, the three-dimensional printing direction of the determined three-dimensional printing model is used for the entity. Print.

From the experimental data, it can be shown that when the three-dimensional printing model is printed as a three-dimensional printing model, printing parameters such as printing layer thickness precision, model thickness, filling ratio and printing rate, etc., under the same printing parameters, When the three-dimensional printing model can be placed under the action of gravity, the total angle of the sum of the plane and the horizontal plane of the outer contour is smaller, if the angle of the sum is limited to the three-dimensional printer Within the print angle, fewer external support structures are required, resulting in fewer print consumables and wasted external support consumables. For the above reasons, the present embodiment performs gravity scrolling simulation on the three-dimensional printing model, and determines the placement position of the three-dimensional printing model using the least external support under the action of gravity, thereby improving the printing quality in the subsequent true printing.

FIG. 1 is a flow chart of a method for self-adjusting a printing direction of a three-dimensional model printing method according to an embodiment of the present invention, and the specific steps thereof are as follows. Step 101: Perform a gravity scrolling simulation on the three-dimensional printing model to determine a placement position of the three-dimensional printing model using the least external support under the action of gravity. Step 101 is performed by simulation of the software, that is, gravity scrolling simulation of the three-dimensional printing model through the software to determine the placement position of the three-dimensional printing model under the action of gravity with the least external support. In step 101, the determined three-dimensional printing model may be one or more of the placement positions using the least external support under the action of gravity.

Step 102: After simulating the three-dimensional printing model according to the determined placement position, the three-dimensional printing model is simulated and sliced to determine a three-dimensional printing direction of the three-dimensional printing model. Step 102 is also performed by simulation of a software. The so-called analog slice refers to a slice of each slice corresponding to the sliced three-dimensional print model after performing simulation slicing on the three-dimensional print model placed at the placement position. The printing control command converts the printing control command into a graphic code (GCode) for printing, thereby knowing the direction and angle of the three-dimensional printing model slice, and determining the three-dimensional printing direction of the three-dimensional printing model, the sliced The method and angle ensure that the least external support is used. Further, the simulated sliced According to the parameters of the 3D printer, it is also possible to estimate the printing time and printing materials such as printing materials.

In an embodiment of the invention, the gravity scrolling simulation is a drop in a gravity environment by simulating a three-dimensional printing model in a three-dimensional coordinate system. Generally, it is divided into three steps to determine the position of the three-dimensional printing model using the least external support under the action of gravity: First, by performing the gravity rolling simulation, the position of the three-dimensional printing model can be naturally static as the initial position; Second, the three-dimensional printing model starts from the initial position, and the object is scrolled under the simulated gravity condition, so that the three-dimensional printing model reaches a stable position of natural stability; third, the three-dimensional space coordinates of the natural stable placement position are recorded, As a three-dimensional coordinate that determines the placement position of the three-dimensional printing model using the least external support under the action of gravity. Here, since the three-dimensional printing model can be naturally placed in the determined three-dimensional space coordinates, the subsequent printing by the placement position is advantageous for the natural molding of the three-dimensional printing model, and the additional external support is minimized.

In the above description, the way to determine whether the three-dimensional printing model can remain stationary at the placement position is by gravity scrolling simulation. That is, by determining the consistency between the center of gravity of the three-dimensional printing model and the direction of gravity, and combining the features of the three-dimensional printing model contacting the horizontal plane to determine whether the three-dimensional printing model can remain stationary at the placement position, and also by means of the three-dimensional column The deviation between the center of gravity of the printed model and the direction of gravity to determine the position of the three-dimensional printing model at rest, the position of the static position will affect the stability of the three-dimensional printing model, that is, through the preset static deviation value, when three-dimensional printing After the deviation between the center of gravity of the model and the direction of gravity reaches the preset static deviation value, the placement position of the static three-dimensional printing model is determined. FIG. 2 is a schematic diagram showing the deviation between the center of gravity and the direction of gravity of the three-dimensional printing model according to an embodiment of the present invention.

In the second step of the above description, the object is scrolled by the simulated gravity condition, and has a scrolling direction. The scrolling direction is selected by centering the gravity direction of the initial position of the three-dimensional printing model and 360 degrees around the gravity plane. Divide the angle to choose. The gravity ground plane is a horizontal plane where the intersection of the longitudinal direction where the gravity direction is located and the lateral direction where the center of gravity is located.

FIG. 3 is a schematic diagram of a scrolling direction of a gravity scrolling simulation according to an embodiment of the present invention. FIG. 3 is only an example, and is not intended to limit the present invention, and specifically includes the following steps. First, it will be divided into 4 parts by 360 degrees around the gravity ground plane. The equal gravity ground plane will form 4 areas, and each of the 4 areas will have the area direction, that is, 1, 2, 3 shown on the 3rd figure. In four directions, the three-dimensional printing model is parabolically tested in four directions: 1, 2, 3, and 4. After the three-dimensional printing model is naturally stabilized by gravity simulation, the three-dimensional space coordinates of the placement position are recorded, assuming The parabola test of the 3D printing model is performed in all four directions, and the determined position of the three-dimensional printing model is Ni (i = 1, 2, 3... n). Secondly, after horizontally shifting and rotating the three-dimensional coordinate coordinates of the placement position Ni, after filtering out the same placement position, the placement position of the screened three-dimensional printing model is obtained (j=1, 2, 3,...m),m is less than n; thirdly, after the swaying simulation of the preset position of the three-dimensional printing model Nj, the stability of the placement position Nj is obtained, and the highest stability is placed. The position Nj serves as a naturally stable placement position as the three-dimensional printing model.

In an embodiment of the invention, before the step 102 is provided, the three-dimensional model printing method further comprises performing projection contour analysis on the three-dimensional printing model, To determine the external support required for each position of the three-dimensional printing model, select the optimal placement position of the external support as the determined placement position. This step is an optional step. When the three-dimensional printing model determined in step 101 is placed at a single position using the least external support under the force of gravity, the step can be omitted directly.

In an embodiment of the present invention, the projection contour analysis analyzes the spatial contour data of the three-dimensional printing model placement position, and further optimizes the selection of the printing direction for the three-dimensional printing model that requires external support. And determining the external support used to determine if the placement of the three-dimensional printing model would result in additional external support resulting in increased consumables and printing time. Specifically, each of the placement positions Nj of the three-dimensional printing model is subjected to segmentation angle projection to analyze the outer contour feature, and the segmentation angle setting is cut according to the requirement of the printing precision, and the bifurcation angle of the top view of the model is cut. The sub-section is performed, as shown in Fig. 4, and the projection profile analysis is performed after halving 360 degrees. FIG. 4 is a schematic diagram showing the contour projection of a three-dimensional printing model when the projection angle is position 1, 2, and 3 according to an embodiment of the present invention. FIG. 5 is a schematic diagram showing the contour projection of the three-dimensional printing model and the three-dimensional printing model when the positions 1, 2, and 3 shown in FIG. 4 are provided according to an embodiment of the present invention. As shown in the figure, the upper graph in Fig. 5 shows the structure of the three-dimensional printing model at positions 1, 2, and 3. The lower graph in Fig. 5 shows the contour projection of the three-dimensional printing model at positions 1, 2, and 3. The structure is indicated.

The contour projection of the three-dimensional printing model is processed, and the contour curve is identified for curve analysis. Specifically, the parallel line of the bottom position of the three-dimensional printing model is the x-axis, and the placing direction is the y-axis. Establish a spatial coordinate system, with the angle between the tangent of the curve and the x-axis as the angle a, and the angle a is defined as the curve The arc needs to produce an external support to print the angle. If the angle a is greater than or equal to 0, but less than 90 degrees, and there is no three-dimensional printing model entity support below the angle a, the label is marked. As shown in the curved surface 520 in the circle in FIG. 5, after obtaining the position of the three-dimensional printing model corresponding to the curved surface 520, the cumulative curved surface area of the corresponding three-dimensional printing model is calculated, and the cumulative curved surface area of the placing position Nj is assumed to be Sj. Then, the simulation slice analysis is performed on the placement position Nj corresponding to the set minimum cumulative surface area Sj.

FIG. 6 is a flowchart of a method for performing projection contour analysis on a three-dimensional printing model according to an embodiment of the present invention, and the specific steps are as follows. Step 601: Obtain a current angle projection view of the three-dimensional printing model. Step 602: Perform contour curve recognition on the projection image. Step 603: Propose a feature position according to the result of the contour curve identification. Step 604: Record the spatial position of the three-dimensional printing model corresponding to the feature position. Step 605: Determine whether the obtained spatial position is already included in the three-dimensional printing model itself. If yes, replace the current angle with the next angle, and return to step 601 to execute; if not, execute step 606. Step 606: Analyze the outer contour surface feature of the three-dimensional printing model. Step 607: Calculate a cumulative curved surface area of the position of the corresponding three-dimensional printing model. Step 608: Determine that the projection maps of all angles are completed. If yes, execute step 609; if not, replace the current angle with the next angle, and return to step 601 for execution. Step 609: The placement position Nj corresponding to the minimum cumulative curved surface area Sj is taken as the optimal placement position of the external support as the placement position determined by the three-dimensional printing model.

FIG. 7 is a schematic diagram of a system structure of a three-dimensional model printing system for self-adjusting printing directions according to an embodiment of the present invention, including a gravity rolling mode The unit 720 and the analog slicing unit 760. The gravity scrolling simulation unit 720 is configured to perform a gravity scrolling simulation on the three-dimensional printing model to determine a placement position of the three-dimensional printing model using the least external support under the action of gravity. The simulation slicing unit 760 is configured to simulate the three-dimensional printing model according to the determined placement position, and then perform simulation slicing on the three-dimensional printing model to determine the three-dimensional printing direction of the three-dimensional printing model.

In the three-dimensional printing system, a projection contour analysis unit 740 may be further included for analyzing the projection contour of the three-dimensional printing model to determine the external support required for each position of the three-dimensional printing model, and selecting the external support therein The optimal placement position is used as the determined placement position.

The present invention has been described in detail with reference to the preferred embodiments of the present invention. All modifications, equivalent substitutions and improvements made within the spirit and scope of the invention are intended to be included within the scope of the invention.

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Claims (10)

A three-dimensional model printing method for self-adjusting the printing direction comprises: performing a gravity rolling simulation on a three-dimensional printing model, determining that the three-dimensional printing model obtains a placement position with a minimum external support under the action of gravity; After the three-dimensional printing model is placed on the placement position of the minimum external support, a three-dimensional printing model is simulated to determine a three-dimensional printing direction of the three-dimensional printing model. The method for printing a three-dimensional model according to claim 1, wherein the step of obtaining the placement position of the minimum external support comprises: setting a static positioning position of the three-dimensional printing model to be static by the gravity rolling simulation As an initial position; starting from the initial position, the three-dimensional printing model is scrolled by an object under simulated gravity conditions, so that the three-dimensional printing model reaches a stable position of natural stability; and the stability of natural stability is recorded. A three-dimensional space coordinate of the placement position as the three-dimensional space coordinate of the placement position of the least external support. The method of claim 3, wherein the step of performing the gravity scrolling simulation comprises: determining the consistency of a center of gravity of the three-dimensional printing model with the direction of gravity, and combining the three-dimensional printing model contact. a feature of a horizontal plane to determine whether the three-dimensional printing model can remain stationary at the placement position; At the same time, a static deviation value is preset, and when a deviation value of the gravity center and the gravity direction of the three-dimensional printing model reaches a preset range of the static deviation value, determining a position of the three-dimensional printing model that is still at rest . The method of printing a three-dimensional model according to claim 2, wherein the scrolling of the object under simulated gravity has a scrolling direction, wherein the selecting of the scrolling direction comprises printing the initial position of the model in the three-dimensional The direction of gravity is centered, and the rolling direction is selected by a bisector angle of 360 degrees around a gravity ground plane, wherein the gravity ground plane is one of a lateral direction in which the gravity direction is located and a horizontal direction in which the center of gravity of the three-dimensional printing model is located. The horizontal plane where the junction is located. The three-dimensional model printing method according to claim 4, wherein the gravity direction of the initial position of the three-dimensional printing model is centered, and the halving angle is selected 360 degrees around the gravity ground plane. The step of scrolling includes: dividing 360 degrees around the gravity ground plane by a predetermined number of parts, and dividing the gravity ground plane to form a plurality of regions, each of the regions having an area direction, respectively, in the regions Performing a parabola test on the three-dimensional printing model in the direction, in the gravity rolling simulation, after the three-dimensional printing model is naturally stabilized, recording a three-dimensional coordinate of a position of the three-dimensional printing model; After the horizontal coordinate and the one-rotation transformation of the three-dimensional space coordinates of the placement position, the same position in the placement position is compared and filtered, and the position of the three-dimensional printing model after screening is obtained; as well as After the swaying simulation of the position of the three-dimensional printing model after the screening is performed, a stability of the position of the three-dimensional printing model after screening is obtained, and the pendulum with the highest stability is obtained. The placement position is the stable placement position that is naturally stable as the three-dimensional printing model. The three-dimensional model printing method according to claim 1, wherein the step of simulating the slice comprises: slicing the three-dimensional printing model at the stable placement position; and generating a column corresponding to the slice corresponding to each layer Printing a control command; converting the print control command into a graphic code GCode for printing. The three-dimensional model printing method according to the first aspect of the patent application, before the step of simulating the slice, the three-dimensional model printing method further comprises performing a projection contour analysis on the three-dimensional printing model to determine the three-dimensional printing model. The external support required for the position is selected, and an optimal placement position in which the external support is optimal is selected as the placement position determined by the three-dimensional printing print model. The method of claim 3, wherein the step of performing the projection profile analysis on the three-dimensional printing model comprises: a) obtaining a projection image of the three-dimensional printing model at a current angle, The projection image performs a contour curve recognition; b) according to the result of the contour curve identification, a feature position is proposed, and a spatial position of the three-dimensional printing model corresponding to the feature position is recorded; c) determining whether the spatial position is already in the three-dimensional printing model, and if so, replacing the current angle with the next angle, returning to step a); if not, performing step d); d) analyzing the 3D printing an outer contour surface feature of the model, calculating a cumulative curved surface area corresponding to the position of the three-dimensional printing model; e) determining that the projection map of all angles is completed, and if yes, performing step f); No, the current angle is replaced with the next angle, and the process returns to step a); and f) the position corresponding to the smallest of the cumulative curved surface areas is selected as the optimal placement position of the external support. The placement position determined as the three-dimensional printing model. A three-dimensional printing system for self-adjusting the printing direction, comprising: a gravity rolling simulation unit for performing a gravity rolling simulation on a three-dimensional printing model to determine that the three-dimensional printing model uses minimal external support under the action of gravity a placement position of a minimum external support; and a simulated slicing unit for simulating the placement of the three-dimensional printing model according to the determined placement position of the minimum external support, and then performing a simulated slicing on the three-dimensional printing model To determine a three-dimensional printing orientation of the three-dimensional printing model. The three-dimensional printing system of claim 9, further comprising: a projection contour analyzing unit configured to analyze a projection contour of the three-dimensional printing model to determine a plurality of pendulums of the three-dimensional printing model Position Do not need one of the external supports, and select an optimal placement position in which the external support is optimal as the determined placement position.