Stress compensation method, system, and computer readable medium for three-dimensional printed models

Abstract

The application relates to a stress compensation method, system and computer readable medium for a three-dimensional printing model. The stress compensation method for the three-dimensional printing model comprises the following steps: obtaining the contour of a design model; determining a first direction and a recess according to the geometric features of the contour, the recess being recessed in the first direction, the recess having a recess end, and the recess end being the lowest point of the contour; establishing a correction coordinate system with the recess end as the origin, the first direction as the longitudinal axis and a second direction perpendicular to the first direction as the transverse axis; judging whether the design model needs to be corrected according to the geometric features of the contour; and correcting the vertex of the design model in the correction coordinate system when the design model needs to be corrected, so that the vertex moves towards the longitudinal axis. The application can compensate for the deformation of a formed model caused by stress and reduce the difference between the formed model and the design model.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the technical field of three-dimensional printers, and in particular to a stress compensation method, system and computer readable medium for a three-dimensional printed model. BACKGROUND

[0002] Three-dimensional (3D) printing technology is a technology that uses a computer three-dimensional design model as a blueprint, through software layering and a numerical control forming system, and by means of a laser beam, a hot melt nozzle, and the like, to perform layer-by-layer accumulation and bonding of metal powder, ceramic powder, plastic, cell tissue, and other special materials, and ultimately to form a solid product. The forming method of three-dimensional printing technology is constantly evolving. Among various forming methods, the light solidification method is a relatively mature method. The light solidification method uses the principle that a light solidification material is cured after being irradiated by ultraviolet light, to perform material accumulation and forming, and has the characteristics of high forming precision, good surface finish, and high material utilization rate.

[0003] Figure 1 is a top view of a three-dimensional model having an arch-shaped geometric feature. For a three-dimensional model such as a tooth model, the middle part protrudes in one direction, and the two ends extend in the opposite direction, forming a U-shaped opening. Since this shape is similar to a curved arch, this structure is referred to as an arch-shaped structure. In 3D printing using the light solidification method, when a three-dimensional model having an arch-shaped structure is printed, thermal stress caused by temperature changes can cause the printed three-dimensional model to expand and deform outward. Figure 1 As shown in FIG. 1, the design model 110 having an arch-shaped structure is the original design of the three-dimensional model, and the formed model 120 is obtained after 3D printing using the light solidification method. The formed model 120 has a U-shaped opening of the arch-shaped structure that is significantly expanded compared to the design model 110. Figure 1 As shown in FIG. 2, the design model 110 has two original ends 111, 112, and the formed model 120 obtained after printing has two printed ends 121, 122. Obviously, the printed ends 121, 122 are offset from the positions of the original ends 111, 112, causing deformation of the formed model 120. SUMMARY

[0004] The present application mainly relates to the technical field of three-dimensional printers, and in particular to a stress compensation method, system and computer readable medium for a three-dimensional printed model.

[0005] The application adopts the technical scheme of a stress compensation method for a three-dimensional printing model to solve the above technical problems, and is characterized by comprising the following steps: obtaining the contour of a design model; determining a first direction and a recess according to the geometric features of the contour, wherein the recess is recessed in the first direction, the recess has a recess end, and the recess end is the lowest point of the contour; establishing a correction coordinate system with the recess end as the origin, the first direction as the longitudinal axis, and the second direction perpendicular to the first direction as the transverse axis; determining whether the design model needs to be corrected according to the geometric features of the contour; and correcting the vertex of the design model in the correction coordinate system when the design model needs to be corrected, so that the vertex moves towards the longitudinal axis.

[0006] In an embodiment of the application, when the design model needs to be corrected, the transverse coordinates of all the vertices of the design model are corrected.

[0007] In an embodiment of the application, the geometric features at least include a first width of the contour on the left side of the origin and a second width of the contour on the right side of the origin; in the correction coordinate system, the first transverse coordinate of the leftmost point is obtained from the feature points on the left side of the origin on the contour, and the absolute value of the first transverse coordinate is taken as the first width; the second transverse coordinate of the rightmost point is obtained from the feature points on the right side of the origin on the contour, and the absolute value of the second transverse coordinate is taken as the second width; and the step of determining whether the design model needs to be corrected according to the geometric features of the contour comprises the following steps: calculating the width ratio of the first width and the second width, and correcting the design model when the width ratio is within a first range.

[0008] In an embodiment of the present application, the recessed end is located at a first side of the profile, the profile has a second side opposite to the first side, the second side has a protruding end protruding to the first direction, the method further comprises: taking the absolute value of the longitudinal coordinate of the protruding end as a base height in the modified coordinate system; the geometric features further comprise a left arm height and a right arm height, a first highest point with the largest absolute value of longitudinal coordinate is obtained from feature points on the profile left of the origin in the modified coordinate system, a second highest point with the largest absolute value of longitudinal coordinate is obtained from feature points on the profile right of the origin in the modified coordinate system, the absolute value of the longitudinal coordinate of the first highest point is taken as the left arm height, and the absolute value of the longitudinal coordinate of the second highest point is taken as the right arm height; the step of judging whether the design model needs to be modified according to the geometric features of the profile further comprises: calculating a first height ratio of the left arm height and the base height, calculating a second height ratio of the right arm height and the base height, and when the first height ratio is within a second range and the second height ratio is within a third range, the design model needs to be modified.

[0009] In an embodiment of the present application, when the design model needs to be modified, only the vertex with the longitudinal coordinate greater than 0 is modified.

[0010] In an embodiment of the present application, the first range is 0.5 to 2.

[0011] In an embodiment of the present application, the second range is greater than or equal to 2.

[0012] In an embodiment of the present application, the third range is greater than or equal to 2.

[0013] In an embodiment of the present application, the horizontal coordinate of all vertices of the design model is modified according to the following formula:

[0014] Dx=Vx+d1

[0015] d1=g1(Vx,Vy)=-p*Vx*Vy*(1-0.5 0.125*|Vx| )

[0016] wherein Dx is the horizontal coordinate of the modified vertex, Vx is the horizontal coordinate of the vertex before modification, Vy is the longitudinal coordinate of the vertex before modification, d1 is the modification value, g1 represents the name of the experience function, and p represents a variable parameter set according to experience.

[0017] In an embodiment of the present application, the horizontal coordinate of the vertex with the longitudinal coordinate greater than 0 is modified according to the following formula:

[0018] Dx=Vx+d2

[0019]

[0020] wherein Dx is the corrected horizontal coordinate of the vertex, Vx is the horizontal coordinate of the vertex before correction, Vy is the vertical coordinate of the vertex before correction, d2 is the correction value, g2 represents an empirical function name, and p represents a variable parameter set according to experience.

[0021] The present application also proposes a stress compensation system for a three-dimensional printing model, comprising: a memory for storing instructions executable by a processor; and the processor for executing the instructions to implement the method as described above.

[0022] The present application also proposes a computer readable medium storing computer program code, which, when executed by a processor, implements the method as described above.

[0023] The present application analyzes the contour of the design model of the three-dimensional printing model, establishes a proper correction coordinate system, and determines whether the design model needs to be corrected according to the geometric characteristics of the contour in the correction coordinate system. If the design model needs to be corrected, the vertex of the design model is corrected in the correction coordinate system. The stress compensation method of the present application can compensate for the deformation of the formed model caused by stress by correcting the coordinates of the vertex, reduce the difference between the formed model and the design model, and thus more meet the design requirements. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings, in which:

[0025] Figure 1 is a top view of a three-dimensional model with an arch-shaped geometric feature;

[0026] Figure 2 is an exemplary flowchart of the stress compensation method for a three-dimensional printing model according to an embodiment of the present application;

[0027] Figure 3 is a contour diagram of a design model in the stress compensation method according to an embodiment of the present application;

[0028] Figure 4A is an effect diagram of the stress compensation method according to an embodiment of the present application;

[0029] Figure 4B is Figure 4A is an enlarged diagram of part of the structure in

[0030] Figure 5 is a system block diagram of the stress compensation system for a three-dimensional printing model according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0032] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application, however, can be practiced without the specific details. In other instances, well-known methods, procedures and devices have not been described in detail so as not to obscure the present application.

[0033] As used in this application and the claims, the terms "one", "a", "an" and / or "the" include both singular and plural referents unless the context clearly dictates otherwise. The terms "comprising", "having", "including", and the like can be used interchangeably with "containing" in the description and claims of this application.

[0034] The relative arrangement of components and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the application unless otherwise specifically stated. It is to be understood that the drawings are not necessarily to scale, and that a particular feature or element that is shown in one drawing can be positioned in a different drawing and / or described in a different section of this document without departing from the scope and spirit of the application. Techniques, methods, and apparatus known to those of ordinary skill can not be discussed in detail because such techniques, methods, and apparatus are considered to be part of the base art. In all examples shown and discussed herein, any specific value is to be interpreted as illustrative only and not as a limitation. Thus, other examples of the exemplary embodiments can have different values. It is to be noted that like numbers and letters refer to like elements throughout the several views of the drawings and that one or more specific embodiments can not reflect every aspect of the application and that the description, therefore, can not completely define not every embodiment. Thus, other embodiments of the application will be apparent to one of ordinary skill in the art from this disclosure.

[0035] In the description of the present application, it should be understood that the orientation words such as "front", "back", "up", "down", "left", "right", "transverse", "vertical", "horizontal", and "top", "bottom" and the like indicate the orientation or positional relationship shown in the drawings generally for the purpose of describing and simplifying the present application, and do not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the scope of protection of the present application. The orientation words "inner", "outer" refer to the inner and outer relative to the contour of the components themselves.

[0036] For purposes of the description hereinafter, spatially relative terms, such as "above", "below", "up", "down", "between", "within", "left", "right", "rear", "front", "upper", "lower", "horizontal", "vertical", "above", "below", "up", "down", "top", "bottom", "under" and the like, can be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is inverted, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The terms "first", "second", "third", etc., do not necessarily indicate any ordinal, chronological or other sequence unless expressly stated to do so.

[0037] In addition, it should be noted that the use of "first", "second", etc. words to define parts is merely intended to distinguish one part from another, and unless otherwise stated, the above words do not have special meanings and should not be interpreted as limiting the scope of protection of the present application. In addition, although the terms used in the present application are selected from well-known and commonly used terms, some terms mentioned in the specification of the present application can be selected by the applicant according to his or her judgment, and the detailed meanings thereof are described in the relevant part of the description. In addition, the present application is required to be understood not only by the actual terms used, but also by the meaning implied by each term.

[0038] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in sequence. On the contrary, various steps can be processed in reverse order or simultaneously. Meanwhile, or other operations are added to these processes, or one or more steps are removed from these processes.

[0039] Figure 2 is an exemplary flowchart of a stress compensation method of a three-dimensional printing model according to an embodiment of the present application. Referring to FIG. 10, the stress compensation method of the embodiment includes the following steps: Figure 2

[0040] Step S210: obtaining the contour of the design model;

[0041] Step S220: determining the first direction and the recess according to the geometric features of the contour, the recess being recessed in the first direction, the recess having a recess end, the recess end being the lowest point of the contour;

[0042] Step S230: establishing a correction coordinate system with the recess end as the origin, the first direction as the longitudinal axis, and the second direction perpendicular to the first direction as the transverse axis;​

[0043] Step S240: judging whether the design model needs to be modified according to the geometric features of the contour; and

[0044] Step S250: when the design model needs to be modified, modifying the vertex of the design model in the modified coordinate system, so that the vertex moves towards the longitudinal axis.

[0045] The following will be described in detail Figure 3 The steps S210-S250 will be described in detail.

[0046] In step S210, the contour of the design model refers to the outer contour of the designed three-dimensional model to be printed. The present application does not limit the method for obtaining the contour of the design model. Those skilled in the art can obtain the contour of the design model by various technical means in the art. For example, the contour of the three-dimensional model can be directly obtained in the design software of the three-dimensional model, or the contour of the three-dimensional model can be obtained through post-image processing.

[0047] Figure 3 is a schematic diagram of the contour of the design model in the stress compensation method of an embodiment of the present application. Referring to Figure 3 , a contour 300 of a design model with an arch structure is shown. Figure 3 The viewing angle shown is a top view or a bottom view. Generally, in the process of three-dimensional printing, the design model is processed in layers to obtain a plurality of layers of printing patterns, and the three-dimensional model is printed layer by layer on the printing platform of the three-dimensional printer according to the printing patterns. Figure 3 The angle shown is also the top view angle of each layer of printing patterns. Therefore, Figure 3 The design model shown has a certain height in the direction perpendicular to the paper, and the contour 300 represents the outermost contour of the design model. It is defined that Figure 3 the direction perpendicular to the paper is defined as the direction axis Z.

[0048] Referring to Figure 3 , the contour 300 has a recessed portion 310 recessed in a first direction D1. According to Figure 3 the contour 300 shown, it can be seen that the design model has an arch structure, and therefore the molded model obtained after the process of three-dimensional printing can have a deformation problem of opening expansion.

[0049] Figure 3 The specific shape of the contour 300 and the shape and number of the recessed portions are not limited, the contour 300 can have a plurality of recessed portions, and the recessed depths of each recessed portion can be different.

[0050] Referring to Figure 3As shown, in step S220, the first direction D1 and the recess 310 are determined according to the geometric features of the profile 300. The recess 310 is recessed in the first direction D1, and the recess 310 has a recess end 311 which is the lowest point of the profile 300. It can be understood that for a profile 300 having multiple recesses, each recess has a lowest recess point as the valley point. For the entire profile 300, the lowest valley point of the profile 300 is the valley point with the lowest position. Therefore, in the embodiment having one recess, as shown in FIG. 3B, the recess end 311 of the recess 310 determined in step S220 is the lowest valley point of the profile 300; and in the embodiment having multiple recesses, the recess 310 determined in step S220 is the recess having the lowest valley point. Figure 3 As shown, the recess end 311 of the recess 310 determined in step S220 is the lowest valley point of the profile 300; and in the embodiment having multiple recesses, the recess 310 determined in step S220 is the recess having the lowest valley point.

[0051] The present application does not limit the specific method for obtaining the first direction D1 and the recess 310.

[0052] In some embodiments, by software setting, the profile image of the design model can be set in a predetermined direction, so that the first direction D1 is parallel to the longitudinal axis of the correction coordinate system to be established, and then the first direction D1 and the recess 310 can be conveniently obtained. For example, for a dental model, the direction of the profile image is adjusted as shown in FIG. 3B, so that the recess 310 of the profile image is recessed in the first direction D1 as shown in FIG. 3B, and then the longitudinal axis direction of the correction coordinate system is parallel to the first direction D1. After the recess 310 is obtained, the valley point thereof can be conveniently obtained as the recess end 311. Figure 3 Figure 3 In some embodiments, by software setting, the profile image of the design model can be set in a predetermined direction, so that the first direction D1 is parallel to the longitudinal axis of the correction coordinate system to be established, and then the first direction D1 and the recess 310 can be conveniently obtained. For example, for a dental model, the direction of the profile image is adjusted as shown in FIG. 3B, so that the recess 310 of the profile image is recessed in the first direction D1 as shown in FIG. 3B, and then the longitudinal axis direction of the correction coordinate system is parallel to the first direction D1. After the recess 310 is obtained, the valley point thereof can be conveniently obtained as the recess end 311.

[0053] In other embodiments, the profile image of the design model can be set in an arbitrary direction instead of being set in the direction as shown in FIG. 3B. In these embodiments, an arbitrary direction can be taken as the initial direction, a candidate recess is searched in the direction, and the related parameters are calculated; then a smaller angle (e.g. 1°) is taken as the increment, all possible directions are traversed, and the related parameters in all directions are calculated; finally, according to the related parameters, it is determined which direction is the first direction. Referring to FIG. 4, it is assumed that the current direction is the first direction D1 as shown in FIG. 3B, and a candidate recess 310 having the lowest valley point is determined. The origin O is taken as the recess end of the candidate recess 310, and the left arm height h1, the right arm height h2, the first width w1, the second width w2 and the base height h0 are calculated, so that: Figure 3 Figure 3 Figure 3

[0054]

[0055] ​​​​

[0056] T = UV

[0057] After traversing all directions of contour 300, the direction that maximizes T will be taken as the first direction D1 in this step. The specific meanings of the left arm height h1, right arm height h2, first width w1, second width w2, and base height h0 will be explained later.

[0058] According to step S230, a corrected coordinate system can be established. This corrected coordinate system has the concave end 311 as the origin O, the first direction D1 as the vertical axis Y, and the second direction D2, which is perpendicular to the first direction D1, as the horizontal axis X. Figure 3 As shown. It should be noted that the vertical axis Y has a positive and a negative direction. According to... Figure 3 The positive direction of the vertical axis Y is consistent with the opposite direction D1' of the first direction D1, and the positive direction of the vertical axis Y points to... Figure 3 Above. Similarly, the horizontal axis X also has positive and negative directions, according to... Figure 3 The horizontal axis X is perpendicular to the first direction D1, and its positive direction is taken as the right side of the horizontal axis X. In other embodiments, the positive direction of the vertical axis Y can also be directed towards... Figure 3 The direction below the x-axis, or taking the left side of the x-axis as its positive direction, has no effect on the stress compensation method of the present invention.

[0059] This instruction manual is Figure 3 The direction indicated by the arrow on the horizontal axis X, i.e., to the right of the horizontal axis X, is taken as its positive direction, while the direction indicated by the arrow on the vertical axis Y, i.e., above the vertical axis Y, is taken as its positive direction.

[0060] According to the corrected coordinate system established in step S230, some feature points of contour 300 are located above the X-axis and have positive ordinates; some feature points are located below the X-axis and have negative ordinates.

[0061] refer to Figure 3 As shown, in step S240, it is determined whether the design model needs to be modified based on the geometric features of contour 300. Experimental results indicate that not all 3D models with an arc-shaped structure require modification. In step S240, the operator can determine whether the design model needs modification based on practical experience. In this embodiment, the geometric features of contour 300 are not limited. Combined with... Figure 3 As shown, this geometric feature may include the depth of the recess, the width of the recess opening, etc. (Reference) Figure 3 As shown, the contour 300 can be composed of two contour lines. Depending on the position, the two contour lines can be divided into a first side 301 and a second side 302. The contour 300 has a certain thickness T1 at different parts, which is the distance between the first side 301 and the second side 302. The geometric features can also include the thickness T1 of each different part.

[0062] If it is determined that the design model needs to be modified after the judgment, the vertex of the design model is modified in the modified coordinate system so that the vertex moves toward the longitudinal axis. In the light-curing three-dimensional printing technology, a three-dimensional model is usually composed of definitions of a plurality of triangular or polygonal patches, each patch including three-dimensional coordinates of each vertex of the triangular or polygonal patch. In an embodiment of the present application, the modification of the design model is to modify the three-dimensional coordinates of each vertex of the design model so that the vertex to be adjusted moves toward the direction close to the origin O.

[0063] It can be understood that, since the arch-shaped structure model is prone to cause the opening of the recessed part to expand outward after being printed and formed, in step S250, the vertex on the design model is moved toward the longitudinal axis by a certain distance to compensate for the deformation after printing and reduce the difference between the formed model and the design model. In other words, the modification of the design model in step S250 is to move part or all of the vertices of the design model, the moving direction of the vertex is opposite to the deformation direction of the vertex, and the moving distance of the vertex is equal to the distance of the vertex deviating from the original position. In this embodiment, the moving distance of the vertex is not limited, and the operator can set it according to experience. In this embodiment, any one or more of the X coordinate, the Y coordinate and the Z coordinate of the vertex can be moved to move the vertex toward the longitudinal axis. Referring to Figure 3 The design model is placed in the modified coordinate system, and the X coordinate and the Y coordinate of the three-dimensional coordinates (x, y, z) of the vertex of the design model can be determined by the X axis and the Y axis of the modified coordinate system shown in Figure 3 The Z coordinate is perpendicular to the X-Y plane direction.

[0064] In some embodiments, the X coordinate and the Y coordinate of the vertex are both modified in step S250 to move the modified vertex toward the longitudinal axis. In these embodiments, only the X coordinate and the Y coordinate of the vertex are modified, and the Z coordinate does not need to be modified. It can be understood that, in order to move the vertex toward the longitudinal axis, the X coordinate can only move toward the direction close to the origin O, and the Y coordinate can move toward the positive direction of the Y axis or the negative direction of the Y axis.

[0065] In some embodiments, the X coordinate and the Y coordinate of all the vertices of the design model are modified in step S250.

[0066] In some embodiments, after the judgment in step S240, it is determined that the design model needs to be modified, and the X coordinate of all the vertices of the design model is modified so that the X coordinate of all the vertices moves toward the longitudinal axis. As Figure 3As shown, the horizontal coordinates of some of the vertices of the design model are located above the horizontal axis X, and the horizontal coordinates of some of the vertices of the design model are located below the horizontal axis X. It can be understood that the correction values of different vertices can be determined according to the actual deformation degree. For example, the deformation degree of the vertices on the design model closer to the origin O is smaller, and the correction value can be smaller; the deformation degree of the vertices on the design model farther away from the origin O is larger, and the correction value can be larger. The correction values of different vertices can be obtained according to an empirical formula or model training, etc.

[0067] According to these embodiments, only the horizontal coordinates of the vertices need to be corrected, and the vertical coordinates of the vertices do not need to be corrected. In Figure 3 In the correction coordinate system shown, the horizontal coordinates of the vertices are translated towards the direction close to the vertical axis. According to these embodiments, the Y coordinates and Z coordinates of the vertices do not need to be corrected, and the correction process is simple and easy to implement.

[0068] In some embodiments, the geometric features in step S240 at least include a first width w1 and a second width w2. Referring to Figure 3 As shown, the first width w1 refers to the width of the contour 300 on the left side of the origin O; the second width w2 refers to the width of the contour 300 on the right side of the origin O. In the correction coordinate system, the width of the contour 300 refers to the length of the contour 300 along the horizontal axis X.

[0069] The first width w1 and the second width w2 in these embodiments are also used to explain the first width w1 and the second width w2 used when the first direction D1 and the recess 310 are determined in step S220.

[0070] The first width w1 and the second width w2 can represent the size and shape of the recess 310. For example, if the first width w1 is greater than the second width w2, it indicates that the recess 310 is offset to the left side; if the first width w1 is less than the second width w2, it indicates that the recess 310 is offset to the right side. The greater the difference between the first width w1 and the second width w2, the greater the degree of offset of the recess 310.

[0071] Specifically, in the correction coordinate system, the first horizontal coordinate of the leftmost point is obtained from the feature points on the left side of the origin O on the contour 300, and the absolute value of the first horizontal coordinate is taken as the first width w1; the second horizontal coordinate of the rightmost point is obtained from the feature points on the right side of the origin O on the contour 300, and the absolute value of the second horizontal coordinate is taken as the second width w2. Here, the feature points on the contour 300 refer to the points on the contour lines that constitute the contour 300. As shown in Figure 3 As shown, the method according to this embodiment can determine the leftmost point 321 and the rightmost point 322 of the contour 300. w1 = |X 321 |, w2 = |X 322 |.

[0072] According to these embodiments, step S240 comprises: calculating a width ratio of the first width w1 and the second width w2, and determining that the design model needs to be corrected when the width ratio is in a first range.

[0073] In some embodiments, the first range is 0.5 to 2. That is, the correction condition in step S240 comprises: determining that the design model needs to be corrected when 0.5≤w1:w2≤2.

[0074] In some embodiments, the abscissa of all vertices of the design model is corrected according to the following formula:

[0075] Dx=Vx+d1 (1)

[0076] d1=g1(Vx,Vy)=-p*Vx*Vy*(1-0.5 0.125*|Vx| ) (2)

[0077] wherein Dx is the abscissa of the corrected vertex, Vx is the abscissa of the vertex before correction, Vy is the ordinate of the vertex before correction, d1 is the correction value, g1 represents the name of an empirical function, and p represents a variable parameter set according to experience.

[0078] According to the above formula (1) and (2), although the ordinate Vy of the vertex before correction is used in formula (2), it is only used to calculate the correction value d1 for correcting the abscissa of the vertex.

[0079] g1 in formula (2) represents an empirical function obtained according to multiple tests. The variable parameter p can be adjusted according to actual conditions. The variable parameter p is related to the printing material, and specifically related to the thermal stress generated after the printing material is heated.

[0080] In some embodiments, both the X coordinate and the Y coordinate of the vertex are corrected. The correction values of the abscissa and the ordinate can be obtained according to formula (2), for example:

[0081] (dx,dy)=g(Vx,Vy)

[0082] Dx=Vx+dx

[0083] Dy=Vy+dy

[0084] The correction value dx of the abscissa and the correction value dy of the ordinate are obtained according to the empirical function g(Vx, Vy), and g is the name of the empirical function.

[0085] Reference Figure 3As shown, in some embodiments, the recessed end 311 is located at the first side 301 of the profile, and the profile 300 has a second side 302 opposite to the first side 301, and the second side 302 has a protruding end 312 protruding to the first direction D1. In these embodiments, the stress compensation method of the present application further comprises the following steps:

[0086] Step S252: obtaining the absolute value of the longitudinal coordinate of the protruding end as the base height in the modified coordinate system;

[0087] Step S254: the geometric features further comprise a left arm height and a right arm height, and the first highest point with the largest absolute value of the longitudinal coordinate is obtained from the feature points on the left side of the origin on the profile, and the second highest point with the largest absolute value of the longitudinal coordinate is obtained from the feature points on the right side of the origin on the profile, and the absolute value of the longitudinal coordinate of the first highest point is taken as the left arm height, and the absolute value of the longitudinal coordinate of the second highest point is taken as the right arm height in the modified coordinate system;

[0088] Step S256: the step of determining whether the design model needs to be modified according to the geometric features of the profile further comprises: calculating a first height ratio of the left arm height and the base height, calculating a second height ratio of the right arm height and the base height, and when the first height ratio is within a second range and the second height ratio is within a third range, the design model needs to be modified.

[0089] In combination Figure 3 As shown, the first side 301 and the second side 302 can be extracted from the profile 300 according to the position of the recessed end 311, and the protruding end 312 can be determined from the second side 302. For the profile 300 with multiple recessed parts, the protruding end 312 corresponds to the recessed end 311.

[0090] In Figure 3 In the embodiments as shown, the transverse coordinates of the recessed end 311 and the protruding end 312 are the same, and the line connecting the two overlaps with the longitudinal axis Y. In other embodiments, the transverse coordinates of the recessed end 311 and the protruding end 312 can be different.

[0091] In step S252, the absolute value of the longitudinal coordinate of the protruding end 312 is obtained as the base height h0.

[0092] Referring to Figure 4A As shown, the longitudinal coordinate of the protruding end 312 is -h0, and its absolute value is taken as the base height h0, indicating that when the design model is arranged in the first direction D1, the part below the X axis is taken as the base of the design model. Figure 4A As shown, the longitudinal coordinate of the protruding end 312 is -h0, and its absolute value is taken as the base height h0, indicating that when the design model is arranged in the first direction D1, the part below the X axis is taken as the base of the design model.

[0093] In some embodiments, the geometric features in step S240 further comprise a left arm height h1 and a right arm height h2, as Figure 4BAs shown, the heights h1 and h2 of the left and right arms represent the lengths or heights of the arm-like structures extending from the left and right sides in the 3D printed model of the bow-shaped structure. Generally, when determining whether to modify the design model in step S240, it can be assumed that the larger the heights h1 and h2 of the left and right arms, the greater the likelihood of deformation of the bow-shaped structure in the printed model.

[0094] Specifically, refer to Figure 4A As shown, in the corrected coordinate system, the first highest point 323 with the largest absolute value of its ordinate is obtained from the feature points on the contour 300 located to the left of the origin O, and the second highest point 324 with the largest absolute value of its ordinate is obtained from the feature points on the contour 300 located to the right of the origin O. The absolute value of the ordinate of the first highest point 323 is taken as the height h1 of the left arm, and the absolute value of the ordinate of the second highest point 324 is taken as the height h2 of the right arm. That is, h1 = |Y| 323 |, h2 = |Y 324 │.

[0095] According to these embodiments, step S240 further includes: calculating a first height ratio of the left arm height h1 to the base height h0, calculating a second height ratio of the right arm height h2 to the base height h0, and when the first height ratio is within a second range and the second height ratio is within a third range, the design model needs to be modified.

[0096] The base height h0, left arm height h1, and right arm height h2 in these embodiments are also used to illustrate the base height h0, left arm height h1, and right arm height h2 used in step S220 when determining the first direction D1 and the recess 310.

[0097] In some embodiments, the second range is greater than or equal to 2. In this case, the correction condition in step S240 further includes: when h1:h0≥2, the design model needs to be corrected.

[0098] In some embodiments, the third range is greater than or equal to 2. In this case, the correction condition in step S240 further includes: when h2:h0≥2, the design model needs to be corrected.

[0099] In some embodiments, when the above-mentioned correction conditions are met, namely: 0.5≤w1:w2≤2, h1:h0≥2, and h2:h0≥2, the design model needs to be corrected. In this case, only the x-coordinates of vertices with ordinates greater than 0 need to be corrected.

[0100] In some embodiments, the x-coordinates of vertices with y-coordinates greater than 0 are corrected according to the following formula:

[0101] Dx=Vx+d2 (3)

[0102]

[0103] wherein Dx is the corrected horizontal coordinate of the vertex, Vx is the horizontal coordinate of the vertex before correction, Vy is the vertical coordinate of the vertex before correction, d2 is the correction value, g2 represents an empirical function, and p represents a variable parameter set according to experience.

[0104] The above formula (4) defines that when the vertical coordinate of the vertex Vy≤0, d2=0, indicating that the vertex does not need to be corrected. Referring to Figure 4A , that is, the vertex in the design model, if it is located below the concave end 311, it does not need to be corrected. According to the formula (3-4), only the horizontal coordinate of the vertex located above the concave end 311 needs to be corrected.

[0105] g2 in formula (4) represents an empirical function, which is obtained according to multiple experiments. The variable parameter p therein is the same as the variable parameter in formula (2).

[0106] In some embodiments, the horizontal coordinate and the vertical coordinate of the vertex with a vertical coordinate greater than 0 are both corrected.

[0107] In some embodiments, the above-mentioned geometric features including the first width w1, the second width w2, the base height h0, the left arm height h1, the right arm height h2, etc. can all be used as parameters to be considered in step S240. These parameters can all be set in the empirical functions g1, g2 or g, and further empirical function results can be obtained according to experimental data for calculating the correction value.

[0108] Figure 4B is an effect schematic diagram of the stress compensation method of an embodiment of the present application. Referring to Figure 4B , the profile of the original design model is the original profile 410, and after the stress compensation method of the present application, the design model is corrected, and the profile of the corrected design model is the corrected profile 420. Obviously, compared with the original profile 410, the width of the concave part of the corrected profile 420 is reduced, which can compensate for the subsequent opening expansion effect caused by the three-dimensional printing process.

[0109] Figure 5 is an enlarged schematic diagram of part of the structure in Figure 5 . As ​ shown, part of the structure in the block 430 is enlarged and shown with ​ , which is located at the end of the left arm-shaped structure of the arch-shaped structure. Referring to ​As shown, in the modified coordinate system, the horizontal coordinate of the vertex 411 located at the end of the original design model is moved to the vertical axis to become the vertex 421 after modification, and the remaining vertices are also modified to have a translation along the vertical axis, and the translation distance is the modification value described above. For some vertices, both the horizontal coordinate and the vertical coordinate are changed.

[0110] In some embodiments, the modification value of the vertical coordinate of a vertex is less than the modification value of the horizontal coordinate of the vertex. For these embodiments, the modification method of the present application fine-tunes the vertical coordinate of the vertex.

[0111] According to the modification method of the present application, the modification values of vertices with different coordinates are also different, so that the profile of the design model is compensated according to the specific position, avoiding overcorrection.

[0112] The present application also includes a stress compensation system for a three-dimensional printing model, comprising a memory and a processor. The memory is used to store instructions executable by the processor; the processor is used to execute the instructions to implement the stress compensation method for the three-dimensional printing model described above.

[0113] ​ is a system block diagram of the stress compensation system for a three-dimensional printing model according to an embodiment of the present application. Referring to ​ As shown, the stress compensation system 500 can include an internal communication bus 501, a processor 502, a read-only memory (ROM) 503, a random access memory (RAM) 504, and a communication port 505. When applied to a personal computer, the stress compensation system 500 can also include a hard disk 506. The internal communication bus 501 can enable data communication between the components of the stress compensation system 500. The processor 502 can make judgments and issue prompts. In some embodiments, the processor 502 can be composed of one or more processors. The communication port 505 can enable data communication between the stress compensation system 500 and the outside. In some embodiments, the stress compensation system 500 can send and receive information and data from the network through the communication port 505. The stress compensation system 500 can also include different forms of program storage units and data storage units, such as the hard disk 506, the read-only memory (ROM) 503, and the random access memory (RAM) 504, which can store various data files used by the computer processing and / or communication, and possible program instructions executed by the processor 502. The processor executes these instructions to implement the main part of the method. The results of the processor processing are transmitted to the user equipment through the communication port and displayed on the user interface.

[0114] The stress compensation method for a three-dimensional printing model described above can be implemented as a computer program, stored in the hard disk 506 and loaded into the processor 502 for execution, to implement the data processing method of the present application.

[0115] The application also includes a computer readable medium having stored thereon computer program code which, when executed by a processor, implements the stress compensation method of a three-dimensional printed model as described above.

[0116] The stress compensation method of a three-dimensional printed model, when implemented as a computer program, can also be stored in a computer readable storage medium as an article of manufacture. For example, the computer readable storage medium can include, but is not limited to, magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips), optical disks (e.g., compact disk (CD), digital versatile disk (DVD)), smart cards, and flash memory devices (e.g., card, stick, key drive). Moreover, the various storage media described herein can represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" can include, without being limited to, wireless channels and various other media (and / or storage media) that are capable of storing, containing, and / or carrying code and / or instructions and / or data.

[0117] It should be understood that the embodiments described above are only illustrative. The embodiments described herein can be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the processors can be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, and / or other electronic units designed to perform the functions described herein, or a combination thereof.

[0118] Some aspects of the application can be performed entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or in a combination of hardware and software. The hardware or software can be referred to as a "block", "module", "engine", "unit", "component", or "system". The processor can be one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, or a combination thereof. Furthermore, aspects of the application can be manifested as a computer product in a machine-readable medium including computer program code. For example, the machine-readable medium can include, but is not limited to, magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips...), optical disks (e.g., compact disk (CD), digital versatile disk (DVD)...), smart cards, and flash memory devices (e.g., card, stick, key drive...).

[0119] A computer readable medium can include a propagated data signal with computer program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal can take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any combination thereof. Computer readable media can be any media that can be accessed by a computer. By way of example, and not limitation, such computer readable media can comprise RAM, ROM, EEPROM, CD-ROM or any combination thereof. The computer program product can be tangibly embodied in an information carrier. The computer program product can also contain instructions that, when executed, perform one or more methods, such as those described above. The computer program product can be tangibly embodied in an information carrier code that can be accessed by a machine and that can cause the machine to perform a series of operations. The operations described above can be implemented as code of any appropriate type on a machine-readable medium.

[0120] The foregoing description has been described in particularity with respect to specific embodiments. Those skilled in the art will recognize that the application is not limited to these specific embodiments. In fact, many modifications and variations are possible in light of the above teachings without departing from the spirit and scope of the application, which is defined by the following claims. It is also noted that carious modifications can be made to the embodiments described above with the scope of the application being defined by the following claims.

[0121] The use of particular nomenclature in reference to the prior art and teachings of the present application is not intended to limit the scope of the application, which is defined by the appended claims. Moreover, the use of particular terminology when describing certain features or aspects of the present application should not be taken to indicate that such terminology is being redefined herein to be restricted to include any specific characteristics of the features or aspects of the application with which that terminology is associated.

[0122] Some embodiments use numerical ranges to describe quantities of components, attributes, etc. It should be understood that the numerical ranges described in the embodiments are approximations. Although the numerical ranges and parameters setting forth the broad scope of these embodiments are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. Any numerical value, however, can contain certain errors associated with testing measurements that exhibit inevitable errors. In some embodiments, the numerical values set forth in the specific examples are reported as precisely as practicable. Any numerical value, however, can contain certain errors associated with testing measurements that exhibit inevitable errors.

Claims

1. A stress compensation method of a three-dimensional printed model, characterized by, The method comprises: obtaining a profile of a design model; determining a first direction and a recess according to geometric features of the profile, the recess being recessed towards the first direction, the recess having a recess end, the recess end being a lowest point of the profile; establishing a correction coordinate system with the recess end as an origin, the first direction as a longitudinal axis, and a second direction perpendicular to the first direction as a transverse axis; judging whether the design model needs to be corrected according to geometric features of the profile, the geometric features including at least a first width of the profile on a left side of the origin and a second width of the profile on a right side of the origin; in the correction coordinate system, obtaining a first transverse coordinate of a leftmost point from feature points of the profile on the left side of the origin, and taking an absolute value of the first transverse coordinate as the first width; obtaining a second transverse coordinate of a rightmost point from feature points of the profile on the right side of the origin, and taking an absolute value of the second transverse coordinate as the second width; the step of judging whether the design model needs to be corrected according to the geometric features of the profile comprises: calculating a width ratio of the first width and the second width, and when the width ratio is within a first range, the design model needs to be corrected; and when the design model needs to be corrected, correcting a vertex of the design model in the correction coordinate system so that the vertex moves towards the longitudinal axis.

2. The stress compensation method of claim 1, wherein, When the design model needs to be corrected, the transverse coordinates of all vertices of the design model are corrected.

3. The stress compensation method of claim 1, wherein, The recess end is located on a first side of the profile, the profile has a second side opposite to the first side, the second side has a protruding end protruding towards the first direction, and the method further comprises: in the correction coordinate system, taking an absolute value of a longitudinal coordinate of the protruding end as a base height; the geometric features further include a left arm height and a right arm height, in the correction coordinate system, a first highest point with a maximum absolute value of a longitudinal coordinate is obtained from feature points of the profile on the left side of the origin, a second highest point with a maximum absolute value of a longitudinal coordinate is obtained from feature points of the profile on the right side of the origin, an absolute value of a longitudinal coordinate of the first highest point is taken as the left arm height, and an absolute value of a longitudinal coordinate of the second highest point is taken as the right arm height; the step of judging whether the design model needs to be corrected according to the geometric features of the profile further comprises: calculating a first height ratio of the left arm height and the base height, calculating a second height ratio of the right arm height and the base height, and when the first height ratio is within a second range and the second height ratio is within a third range, the design model needs to be corrected.

4. The stress compensation method of claim 3, wherein, Further comprising: when the design model needs to be corrected, only the vertices with a longitudinal coordinate greater than 0 are corrected.

5. The stress compensation method of claim 1, wherein, The first range is 0.5 to 2.

6. The stress compensation method of claim 3, wherein, The second range is greater than or equal to 2.

7. The stress compensation method of claim 3, wherein, The third range is greater than or equal to 2.

8. The stress compensation method of claim 2, wherein, The transverse coordinates of all vertices of the design model are corrected according to the following formula: Dx = Vx + d1 d1 = g1(Vx, Vy) = -p*Vx*Vy*(1 - 0.5 0.125*|Vx| ) wherein Dx is the corrected horizontal coordinate of the vertex, Vx is the horizontal coordinate of the vertex before correction, Vy is the vertical coordinate of the vertex before correction, dl is the correction value, gl denotes the name of the empirical function, and p denotes a variable parameter set empirically.

9. The stress compensation method of claim 4, wherein, The horizontal coordinate of the vertex whose vertical coordinate is greater than 0 is corrected according to the following formula: Dx = Vx + d2 wherein Dx is the corrected horizontal coordinate of the vertex, Vx is the horizontal coordinate of the vertex before correction, Vy is the vertical coordinate of the vertex before correction, d2 is the correction value, g2 denotes the name of the empirical function, and p denotes a variable parameter set empirically.

10. A stress compensation system for a three-dimensional printed model, comprising: a memory for storing instructions executable by a processor; a processor for executing the instructions to implement the method of any one of 1-9.

11. A computer readable medium having stored thereon computer program code which, when executed by a processor, implements the method of any one of 1-9.

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