CN115609010A - Forming process and slicing method for metal 3D printing suspension structure - Google Patents

Abstract

The application discloses a forming process and a slicing method of a metal 3D printing suspension structure, which relate to the technical field of 3D printing and comprise the steps of slicing a target part in a layering manner, and obtaining size variable quantities dx and dy of two layers of slices adjacent to each other in the X and Y directions; if dx and dy are less than or equal to 0, printing target parts without support, if dx and dy are greater than a, adding supported printing target parts, if 0-less dx and dy are less than a/2, adopting a transition-area-free slice scanning strategy, and if a/2-less dx and dy are less than a, adopting a transition-area slice scanning strategy; based on a non-transition region or transition region slicing scanning strategy, scanning and filling are carried out according to the principle that the laser energy input density outside the transition region is less than the laser energy input density in the transition region is less than the laser energy input density of the part main body, and a contour scanning path filling strategy is obtained. This application is through optimizing the laser energy input density in the different regions, and the heat that control highlights in the section gathers, reduces the part and appears printing warping risk, realizes the printing of longer highlighting cross-section part.

Description

Forming process and slicing method for metal 3D printing suspension structure

Technical Field

The application relates to the technical field of 3D printing, in particular to a forming process and a slicing method for a metal 3D printing suspension structure.

Background

Additive manufacturing is commonly known as 3D printing, combines computer aided design, material processing and forming technology, and is a manufacturing technology for manufacturing solid articles by stacking special metal materials, non-metal materials and medical biomaterials layer by layer in modes of extrusion, sintering, melting, photocuring, spraying and the like on the basis of digital model files through software and a numerical control system.

The selective laser melting 3D technology is used as an important branch, and selective laser melting 3D printing is a rapid forming technology capable of directly forming high-density and high-precision metal parts, and is particularly suitable for the manufacturing process of parts with complex structures. The manufacturing process of the selective laser melting technology comprises the following steps: a platform in the powder supply bin rises for a certain height according to the powder quantity with a set layer thickness, a powder spreading scraper moves horizontally to uniformly spread metal powder on a substrate of the forming bin, and laser scans and melts the powder in an area needing to be melted under the control of a galvanometer according to a well-sliced scanning path; then the substrate is descended by one layer thickness, the processing process of the upper layer is repeated, and the process is repeated, so that the metal parts are processed layer by layer.

In actual printing and manufacturing, the selective laser melting 3D printing technology often needs to add support to complete printing and forming of the highlighted section. However, the existing selective laser melting forming process, that is, the SLM forming process can form the protruded section within 0-2mm, and cannot complete the printing and forming.

Disclosure of Invention

The application mainly aims to provide a forming process and a slicing method for a metal 3D printing suspension structure, and aims to solve the problem that a long prominent section part cannot be formed by a laser selective melting 3D forming process in the prior art.

The technical scheme adopted by the application is as follows:

a method of metal 3D printing, comprising:

according to the preset printing layer thickness, carrying out layered slicing on a part model corresponding to a target part by using slicing software to obtain a multilayer slice corresponding to the part model;

acquiring the size variation dx of the adjacent upper layer slice and the lower layer slice in the X direction and the size variation dy in the Y direction in the coordinate axis based on the multilayer slices;

if dx and dy are both less than or equal to zero, 3D printing the target part in an unsupported mode;

if dx and dy are both larger than zero, judging whether dx and dy are both larger than a, and if dx and dy are both larger than a, adopting a support adding mode to 3D print the target part; wherein a is the corresponding maximum overhanging length of different printing materials under the unsupported printing condition;

if dx and dy are both smaller than a, judging whether dx and dy are both larger than zero and smaller than a/2, if 0-dx-and-dy-yarn-cover-a/2 and 0-dy-yarn-cover-a/2 are judged, adopting a transition-area-free slice scanning strategy, and scanning according to preset scanning parameters to obtain a scanning path filling strategy; if a/2-dx-and a/2-dy-yarn-a are judged, a transition area section scanning strategy is adopted, and preset scanning parameters in the transition area and outside the transition area are adjusted to scan according to the principle that the laser energy input density outside the transition area is less than the laser energy input density in the transition area is less than the laser energy input density of a part main body so as to obtain a scanning path filling strategy;

printing the target part based on the contour scan path filling strategy.

Optionally, the scanning with the transition-region-free slice scanning strategy according to the preset scanning parameters to obtain the scanning path filling strategy includes:

determining the highlighted cross section to occur in the nth layer of slices, wherein n is the number of layers where the upper layer of slices are located in the two adjacent layers of slices which satisfy that dx and dy are both greater than zero, and the highlighted cross section is a cross section part consisting of dx and dy in the two adjacent layers of slices which satisfy that dx and dy are both greater than zero;

taking the nth layer of slices as a boundary, rotating the slices of 1 to n-1 layers layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of 1 to n-1 layers; wherein the preset angle alpha is 25-40 degrees;

and scanning and filling the slices behind the n layers in a mode of alternately changing the scanning angle in the direction from the original section to the highlighted section, and maintaining the preset scanning parameters for scanning and filling when no transition region exists, so as to obtain a contour scanning path filling strategy behind the n layers.

Optionally, the scanning strategy of the slice with the transition region is adopted, and the preset scanning parameters in the transition region and outside the transition region are adjusted to perform scanning according to the principle that the laser energy input density outside the transition region is less than the laser energy input density in the transition region is less than the laser energy input density of the part main body, so as to obtain the scanning path filling strategy, including:

determining the highlighted cross section to occur in the nth layer of slices, wherein n is the number of layers where the upper layer of slices are located in the two adjacent layers of slices which satisfy that dx and dy are both greater than zero, and the highlighted cross section is a cross section part consisting of dx and dy in the two adjacent layers of slices which satisfy that dx and dy are both greater than zero;

taking the nth layer of slices as a boundary, rotating the slices of 1 to n-1 layers layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of 1 to n-1 layers, wherein the preset angle alpha is 25-40 degrees;

scanning and filling the n-layer to n + (50-100) layer slices in a mode of alternately changing scanning angles in the direction from the original section to the highlighted section, determining the range of the transition region when the transition region exists, adjusting preset scanning parameters, and scanning and filling according to the fact that the laser energy input density of the transition region is larger than the laser energy input density outside the transition region to obtain a contour scanning path filling strategy from the n-layer to the n + (50-100) layer;

and clearing the transition region after the n + (50-100) layers, rotating layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of all slices after the n + (50-100) layers.

Optionally, the scanning and filling the n-layer to n + (50-100) -layer slices in the direction from the original cross section to the highlighted cross section in a manner of alternating scanning angles includes:

in any two adjacent layers of slices, the scanning path of the upper layer of slices and the scanning path of the lower layer of slices form an included angle beta;

wherein beta is 30-40 degrees.

Optionally, the included angle β is 35 °.

Optionally, the preset scanning parameters include a scanning interval, a laser power, and a scanning speed.

Optionally, the determining the range of the transition region includes:

taking the intersecting contour line of the highlighted section and the original section as the inner contour line of the transition area;

acquiring a midpoint coordinate (X1, Y1) and two intersecting endpoint coordinates (X2, Y2) of an inner contour line of the transition region;

extending the midpoint coordinates (X1, Y1) to the highlighted section along the X direction for 6-7 units to obtain the farthest corner point coordinate of the transition area;

smoothly connecting three points determined by the coordinates of the farthest corner point and the coordinates of the two intersected end points by using an arc line to form an outer contour line of the transition region;

and the transition region range is defined by the area enclosed by the outer contour line and the inner contour line.

Optionally, determining the range of the transition region includes:

acquiring the area of the highlighted section;

acquiring two intersecting end points of an inner contour line and an outer contour line of the highlighted section;

and the area of the prominent section is divided equally by using a smooth dividing line, the area between the inner contour line and the dividing line is the transition area range, and the end points of the two ends of the dividing line are superposed with the two intersected end points of the inner contour line and the outer contour line.

Optionally, the slicing a part model corresponding to a target part by using slicing software according to a preset printing layer thickness to obtain a multilayer slice corresponding to the part model includes:

adjusting the placing position of the part model, wherein the part placing requirement is to avoid the phenomenon of reverse scraping in the printing process;

and importing the adjusted part model into slicing software, setting parameters of the slicing software, and finishing layered slicing of the part model through the slicing software.

Optionally, based on the multi-layer slice, obtaining a size variation dx in an X direction and a size variation dy in a Y direction of adjacent upper and lower layers of slices in a coordinate axis, including:

marking the coordinate values of each layer of slices in the X and Y directions corresponding to each angular point by using slice software;

and subtracting the coordinate value of the adjacent lower layer slice from the coordinate value of the upper layer slice to obtain the size change dx and dy.

Compared with the prior art, the beneficial effects of this application are:

compared with the traditional SLM forming process, the forming process and the slicing method for the metal 3D printing suspension structure are provided by the embodiment of the application, based on the judgment of the extension length of the highlighted section, the supporting and non-supporting printing strategies matched with the highlighted section under different extension lengths are provided in a targeted manner, the non-transition-region slicing scanning strategy and the transition-region slicing scanning strategy are correspondingly adopted under the condition that the highlighted section with the highlighted section but without supporting and printing is refined under different extension lengths, based on the characteristic that the highlighted section of a longer area is easy to warp due to thermal aggregation and material expansion and contraction in the heating melting-rapid cooling process, the melting degree of the printed material in the area is weakened by optimizing the laser energy input density in the transition region and the non-transition region, according to the scanning path filling strategy that the highlighted section is lower in the extension length, the laser energy input density is guided to be controlled, the farther area is provided with the relatively lower laser energy input density, the melting degree of the printed material in the area is weakened, the melting state that the printed material is not completely melted in the area, the thermal aggregation and the thermal shrinkage of the material is reduced, the light energy change of the heat shrinkage-shrinkage process of the molded part is reduced, and the final molded product is realized, and the purpose of the 3D molded.

Drawings

Fig. 1 is a process flow diagram of a forming process and a slicing method of a metal 3D printed suspension structure provided in an embodiment of the present application;

FIG. 2 is a schematic cross-sectional view of various types of parts in highlighted form;

FIG. 3 is a schematic view of a section of a curved or flat highlighted section without a transition zone being sliced at the nth layer profile;

FIG. 4 is a schematic view of a contour slice of a curved or flat highlighted cross-sectional part at the (n + 1) th layer without a transition region;

FIG. 5 is a schematic view of a section of a curved or flat highlighted section with a transition zone cut into the profile of the nth layer;

FIG. 6 is a schematic view of a contour slice of a curved or flat highlighted cross-sectional part having a transition region at layer n + 1;

FIG. 7 is a schematic view of a curved or flat surface highlighted cross-sectional part without a transition region scanned along the profile path of the nth layer;

FIG. 8 is a schematic view of scanning the contour path of a curved or flat highlighted cross-sectional part at the (n + 1) th layer without a transition region;

FIG. 9 is a schematic view of scanning the contour path of the (n + 2) th layer of a curved or flat prominent cross-sectional part without a transition zone;

FIG. 10 is a schematic view of a curved or flat surface prominent section part with a transition zone scanned at the nth layer profile path;

FIG. 11 is a schematic view of a curved surface or a flat surface of a protruded section part with a transition region scanning on the (n + 1) th layer profile path;

FIG. 12 is a schematic view of a curved surface or a flat surface with a transition region showing the scanning of the profile path of the part at the n +2 th layer;

FIG. 13 is a schematic view of a scanning of a profile path of a part with a square salient cross section without a transition region on the nth layer;

FIG. 14 is a schematic view of scanning a contour path of a part with a square salient cross-section without a transition region on the n +1 th layer;

FIG. 15 is a schematic view of scanning the contour path of a square-shaped salient cross-section part at the n +2 th layer without a transition region;

FIG. 16 is a schematic view of a scanning of a profile path of a part with a square highlighted cross section having a transition region at the nth layer;

FIG. 17 is a schematic view of scanning the profile path of a square high-profile part with a transition region at the (n + 1) th layer;

FIG. 18 is a schematic view of a scanning of a contour path of a part with a square salient cross-section having a transition region at the n +2 th layer;

FIG. 19 is a schematic view of a curved or flat highlighted cross-sectional feature containing a support structure scanning the profile path of the nth layer;

FIG. 20 is a schematic view of a curved or flat surface highlighted cross-sectional part with a support structure scanning the contour path of the (n + 1) th layer;

FIG. 21 is a schematic view of a curved or flat surface highlighted cross-sectional part with a support structure scanning the contour path of the (n + 2) th layer;

FIG. 22 is a schematic view of a scanning path of a square projection cross-section part with a support structure at the nth layer;

FIG. 23 is a schematic view of a scanning path of a square high profile part with a supporting structure at the n +1 th layer;

FIG. 24 is a schematic view of a scanning path of a square high profile part with a supporting structure at the n +2 th layer;

FIG. 25 is a schematic cross-sectional view of a part in printing with added diagonal bracing;

FIG. 26 is a schematic cross-sectional view of the parts in printing with the addition of vertical support.

The reference numbers in the figures indicate:

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that all directional indicators (such as up, down, left, right, front, back \8230;) in the embodiments of the present application are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In this application, unless expressly stated or limited otherwise, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between the embodiments may be combined with each other, but must be based on the realization of the technical solutions by a person skilled in the art, and when the technical solutions are contradictory to each other or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope claimed in the present application.

Referring to fig. 1, the embodiment of the present application provides a forming process and a slicing method for a metal 3D printing suspension structure, including the steps of:

according to the preset printing layer thickness, carrying out layered slicing on a part model corresponding to a target part by using slicing software to obtain a multilayer slice corresponding to the part model;

based on the multilayer slices, acquiring the size change dx of the adjacent upper-layer slices and lower-layer slices in the X direction and the size change dy in the Y direction in the coordinate axis;

if dx and dy are both less than or equal to zero, 3D printing the target part in an unsupported mode;

if dx and dy are both larger than zero, judging whether dx and dy are both larger than a, and if dx and dy are both larger than a, adopting a support adding mode to 3D print the target part; wherein a is the maximum overhanging length of different printing materials under the condition of unsupported printing;

if dx and dy are both smaller than a, judging whether dx and dy are both larger than zero and smaller than a/2, if 0-dx-Once a/2 and 0-dy-Once a/2 are judged, adopting a transition-area-free slice scanning strategy, and scanning according to preset scanning parameters to obtain a scanning path filling strategy; if judging that the a/2-plus-dx-plus-a and the a/2-dy-plus-a are included, adopting a transition region slice scanning strategy, and adjusting preset scanning parameters in the transition region and outside the transition region for scanning according to the principle that the laser energy input density outside the transition region is less than the laser energy input density in the transition region is less than the laser energy input density of the part main body so as to obtain a scanning path filling strategy;

printing the target part based on the contour scan path filling strategy.

In the 3D printing technology, the selective laser melting technology is used in the selective laser melting manufacturing process of an actual metal powder bed, the metal powder bed is rapidly melted after absorbing laser input energy, and is rapidly cooled along with the movement of a scanning path and the heat transfer of a forming substrate, and the selective laser melting technology is formed through repeated 'rapid heating-rapid cooling' thermal balance and 'layer-by-layer stacking'. As can be seen, the quality of the product formed is very closely related to the laser energy input energy in terms of laser energy input density (E, unit: J/mm) ³ ) Expressed as:

in the above formula:

p-laser input power (unit: W);

v-laser scanning speed (unit: mm/s)

h-scanning distance (unit: mm)

t-thickness of the powder coating (unit: mm)

The following formula (1) shows: the laser input energy density of the metal powder bed is mainly related to four main parameters of laser power, powder spreading thickness, scanning speed, scanning interval and the like, wherein the powder spreading layer thickness t is a fixed value. Taking a certain base alloy as an example, the part can be formed by combining four main parameters and the laser energy input density E =50-100J/mm 3. However, the larger the laser input energy is, the faster the heat conduction speed is required, and the part is formed in the process of 'quick heating-quick cooling' heat balance physical change, if the heat input energy is too large, after the metal powder is completely melted, the longer prominent section is farther away from the part main body, and in the process of quick heating-quick cooling, the longer prominent section is more easily subjected to buckling deformation caused by heat aggregation and expansion and contraction, so that the part printing fails. Therefore, in the case of forming a part, it is effective to reduce the laser energy input density of the powder bed for a certain printed layer (for example, a projected cross-sectional layer) having a relatively large difference in conductivity, thereby preventing deformation.

According to the principle, compared with the traditional SLM forming process, by judging the protruding length of the protruding section, the unsupported printing strategy or the supported printing strategy which is correspondingly adapted to the protruding section under different protruding lengths is provided in a targeted manner, for example, the unsupported printing strategy is adopted under the condition of no protruding section, when the protruding section exceeds a certain length, the supported printing strategy is adopted, the protruding section with the protruding section but without supported printing is refined under different protruding lengths, the transition-region-free slicing scanning strategy and the transition-region slicing scanning strategy are correspondingly adopted, based on the characteristic that the protruding section with the longer region is heated and melted and quickly cooled, the warping is more prone to be caused by heat aggregation and material expansion and shrinkage, the scanning path with the lower laser energy input density in the transition region and the transition-region is optimized according to the region with the longer protruding length, the melting path with the lower laser energy input density is filled, so as to control the laser energy input density, the farther region adopts the relatively lower heat aggregation and warpage, the final heating energy input density in the transition region is reduced, and the change of the material in the fully-heated and-cooled state of the protruding section is reduced, so that the target product is reduced by reducing the heat aggregation and the change in the protruding section.

In the forming process and the slicing method of the metal 3D printing suspension structure provided in this embodiment, specifically for each step, the specific implementation manner is as follows:

with regard to the steps: according to the preset printing layer thickness, slicing a part model corresponding to a target part by using slicing software to obtain a multilayer slice corresponding to the part model, wherein the specific implementation contents comprise:

adjusting the placing position of the part model, wherein the placing requirement of the part is to avoid the phenomenon of reverse scraping in the printing process;

and importing the adjusted part model into slicing software, setting parameters (such as printing layer thickness) of the slicing software, and finishing layered slicing on the part model through the slicing software.

It can be understood that the layer thickness parameter of the slices is in inverse proportion to the number of the slices, the thinner the layering is, the more the number of layers is, the better the model forming effect is, and the longer the corresponding printing time is, so that the selection of the preset thickness needs to meet the advantages of good forming effect and low printing time as much as possible.

In one embodiment, regarding the steps: based on the layered slices, size variation dx and dy in the X and Y directions of the adjacent upper layer slice and lower layer slice are obtained, and the specific implementation manner is as follows:

marking the coordinate values of each layer of slices in the X and Y directions corresponding to each angular point by using slice software;

subtracting the coordinate value of the adjacent lower slice from the coordinate value of the upper slice to obtain the size variable dx and dy;

it is conceivable that the dimensional change amounts dx and dy of the upper layer slice and the lower layer slice in the X and Y directions are important bases for judging the highlight section, whether the adjacent upper layer slice protrudes from the adjacent lower layer slice can be determined based on dx and dy, and the protrusion length of the highlight section is obtained according to the specific values of dx and dy.

The following steps: if dx and dy are both less than or equal to zero, 3D printing the target part in an unsupported mode;

if dx and dy are both larger than zero, judging whether dx and dy are both larger than a, and if dx and dy are both larger than a, adopting a support adding mode to 3D print the target part; wherein a is the corresponding maximum overhanging length of different printing materials under the unsupported printing condition;

if dx and dy are both smaller than a, judging whether dx and dy are both larger than zero and smaller than a/2, if 0-dx-Once a/2 and 0-dy-Once a/2 are judged, adopting a transition-area-free slice scanning strategy, and scanning according to preset scanning parameters to obtain a scanning path filling strategy; if a/2-dx-and a/2-dy-yarn-a are judged, a transition area section scanning strategy is adopted, and preset scanning parameters in the transition area and outside the transition area are adjusted to scan according to the principle that the laser energy input density outside the transition area is less than the laser energy input density in the transition area is less than the laser energy input density of a part main body so as to obtain a scanning path filling strategy;

referring to fig. 2 to 6, it can be understood that dx and dy are the size difference between the upper layer slice and the lower layer slice in the X direction and the Y direction, and therefore, if dx is less than or equal to and dy is less than or equal to 0, it is indicated that the upper layer slice does not protrude out of the lower layer slice, and in the printing process, the upper layer slice always has the lower layer slice as a support, and in the printing process from bottom to top, no additional support needs to be provided for the upper layer slice, so that a unsupported printing strategy is adopted, and it can be imagined that, if a conical part is printed, the lower layer slice of the conical part always serves as a support for the upper layer slice, and thus, no support is needed in the printing process from bottom to top;

on the contrary, if dx >0 and dy >0, the upper layer slice protrudes from the lower layer slice, it is conceivable that if the protruding length is long, printing is performed without support, and it is obvious that the metal powder bed is easy to warp after melting, which affects the printing quality, so it can be understood that when the size variation dx, dy of the upper layer slice and the lower layer slice exceeds a certain value, support needs to be added for printing, and of course, when the size variation dx, dy of the upper layer slice and the lower layer slice is within a certain range, the metal powder bed can bear the warp risk depending on the self-performance, so unsupported printing can be adopted.

Of course, it is understood that in the interval of 0-dx and 0-dy wicks, the greater the probability of occurrence of warp deformation as the highlighted cross-sectional length increases, and therefore, a concept of a transition region is proposed by which the laser power input density is adjusted, and the farther from the part body, a method of decreasing the laser power input density is employed for the purpose of improving the quality of 3D molding of the part, so that the following two cases are divided for the interval of 0-dx and 0-dy wicks:

in one embodiment, see fig. 7-24, the steps: if judging that the number of the 0-plus-dx plus-a/2 and the number of the 0-plus-dy plus-a/2 are judged, adopting a transition-area-free slice scanning strategy, and scanning according to preset scanning parameters to obtain a scanning path filling strategy; the specific implementation steps are as follows:

firstly, determining a prominent cross section to occur in an nth layer of slices, wherein n is the number of layers of upper slices in two adjacent slices of which dx and dy are both greater than zero, and the prominent cross section is a cross section part consisting of dx and dy in two adjacent slices of which dx and dy are both greater than zero;

then, taking the nth layer of slices as a boundary, rotating the slices of 1 to n-1 layers layer by layer according to a preset angle alpha and carrying out scanning filling by using preset scanning parameters to obtain a contour scanning path filling strategy of 1 to n-1 layers; wherein the preset angle alpha is 25-40 degrees;

then, scanning and filling the n layers of later slices in a mode of alternately changing scanning angles in the direction from the original section to the highlighted section, and maintaining the preset scanning parameters for scanning and filling when no transition area exists, so as to obtain a contour scanning path filling strategy after the n layers; it can be understood that since the overhang length of the highlight screen shot is within a controllable range, when no transition region exists, the part can be scanned by adopting laser energy input density which is close to or slightly lower than the main body of the part.

In another embodiment, if it is determined that a/2-plus-dx-plus-a and a/2-plus-dy-plus-a are included, a transition region slicing and scanning strategy is adopted, and preset scanning parameters in the transition region and outside the transition region are adjusted to perform scanning according to the principle that the laser energy input density outside the transition region is less than the laser energy input density in the transition region is less than the laser energy input density of the part body, so as to obtain a scanning path filling strategy, which is specifically implemented by the following steps:

firstly, determining a prominent cross section to occur in an nth layer of slices, wherein n is the number of layers of upper slices in two adjacent slices of which dx and dy are both greater than zero, and the prominent cross section is a cross section part consisting of dx and dy in two adjacent slices of which dx and dy are both greater than zero;

then, taking the nth layer of slices as a boundary, rotating the slices of 1 to n-1 layers layer by layer according to a preset angle alpha, and scanning and filling the slices by using preset scanning parameters to obtain a contour scanning path filling strategy of 1 to n-1 layers; wherein the preset angle alpha is 25-40 degrees;

then, scanning and filling the n layers to the n + (50-100) layers of slices in a mode of alternately changing scanning angles in the direction from the original section to the highlighted section, determining the range of the transition region when the transition region exists, adjusting preset scanning parameters, and scanning and filling according to the condition that the laser energy input density of the transition region is greater than that outside the transition region to obtain a contour scanning path filling strategy from the n layers to the n + (50-100) layers; based on the formula (1) and a corresponding theory, it is not difficult to understand that, taking a certain base alloy as an example, the laser energy input density E =50-100J/mm3 range can be used for forming parts, when printing, the E can be divided into three levels E0, E1 and E2 from large to small, each level represents a value range of the laser energy input density, the E0 is the largest, the E1 is the lowest, and the E2 is the smallest. It will be appreciated that in order to achieve different laser energy input densities in different regions, the scan parameters are adjusted according to equation (1): any one or more of laser input power, laser scanning speed and scanning interval

And finally, clearing the transition region after the n + (50-100) layers, rotating layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of all slices after the n + (50-100) layers.

Here, it should be noted that, the first; in this embodiment, α is selected from a range of 25 ° to 40 °, and its main purpose is to: during unsupported printing, it is not desirable to choose an excessively large rotation angle α, otherwise the printing path cannot be produced. Secondly, the method comprises the following steps: the reason for choosing the n + (50-100) layer as the boundary is as follows: at present, the thickness of the layer is usually 0.02mm, (50-80) layer = (1-2) mm, when the height of the layer is printed according to the current strategy, the transition region is fully fused with the part body, and the variable parameter printing strategy can not be used any more.

Certainly, under some special conditions, for example, some highlighting sections are long in highlighting length, and when the highlighting is performed, the part main body is directly and completely highlighted horizontally at one time instead of being highlighted layer by layer on an inclined plane, at this time, the support printing and the transition area scanning printing and the non-transition area scanning printing can be combined for printing, so that the printing quality of the part can be improved, and the forming precision of the part can be ensured.

In this embodiment, referring to fig. 7 to 24, the scanning and filling of the n-layer to n + (50 to 100) -layer slices in the direction from the original cross section to the highlighted cross section by alternating the scanning angle specifically includes:

in any two adjacent layers of slices, the scanning path of the upper layer slice and the scanning path of the lower layer slice form an included angle beta, so that the scanning paths of any two adjacent layers of slices are different, the superposition of the scanning paths is avoided, the situation that the upper layer metal powder bed and the lower layer metal powder bed are fused into a whole is avoided, the staggered layered scanning can enable the parts to be clear layer by layer, and the printing quality is improved.

In one embodiment, β may be 30 °, 35 °, 40 °, which may exhibit a sharp misalignment without each deflection being too large.

In one embodiment, the determining the transition region range may be performed in the following manner, including the steps of:

taking the intersecting contour line of the highlighted section and the original section as the inner contour line of the transition area;

acquiring the coordinates (X1, Y1) of the middle point of the inner contour line of the transition region and the coordinates (X2, Y2) of two intersected end points;

extending the midpoint coordinates (X1 and Y1) to the highlighted section along the X direction for 6-7 units to obtain the farthest corner point coordinate of the transition area;

smoothly connecting three points determined by the coordinates of the farthest angular point and the coordinates of the two intersected end points by using an arc line to form an outer contour line of a transition area;

the area enclosed by the outer contour line and the inner contour line is the transition area range.

Of course, in another embodiment, the following method may be adopted to determine the transition area range, including the steps of:

acquiring the area of the highlighted section;

acquiring two intersection end points of an inner contour line and an outer contour line of the highlighted section;

and the area of the prominent section is divided equally by using a smooth dividing line, the area between the inner contour line and the dividing line is the range of the transition region, and the end points of the two ends of the dividing line are superposed with the two intersected end points of the inner contour line and the outer contour line.

During the actual printing process, the operator can select any method by himself to determine the extent of the transition region.

In addition, when the mode of adding the support is adopted to 3D print the target part, the specific method comprises the following steps:

judging whether 90-delta min is larger than theta, wherein theta is the minimum inclination angle of the self-supporting printing of the part and delta min is the included angle between the connecting line between the part supporting growth plane A and the part supporting addition plane B and the part supporting growth plane A as shown in figure 1;

if 90-delta min > theta, referring to fig. 25, the length of the highlighted section exceeds a, but the length of the support growth plane a is greater than that of the part support adding plane B, in which case diagonal support printing is added, the support adding plane B is selected first, then the support generation plane a is selected, the included angle delta to be inclined and the support size parameters are input, such as the input of the planned support diameter/up-down diameter, the minimum spacing and the maximum spacing for the cylinder/cone type supports, preferably, the cylinder/cone type diameter is 0.1-3 mm, and the minimum spacing and the maximum spacing are set to be 1-5 mm;

if 90- δ mi ≦ θ, see fig. 26, which illustrates that the highlighted cross-section highlighted length exceeds a, but the length of the part support adding plane B is greater than the length of the support growing plane a, at this time, if adding the diagonal support printing, the tilt angle α between the diagonal support and the part adding support plane B is too large, which results in insufficient support strength and easily causes part printing failure, so the adding of the vertical support printing is selected, the support adding plane B is selected first, then the substrate/part surface is defaulted as the support generating plane, the support size parameters are input, such as the support diameter/up-down diameter, the minimum spacing and the maximum spacing are input for the cylinder/cone support, preferably, the cylinder/cone diameter is 0.1-3 mm, and the minimum spacing and the maximum spacing are set to be 1-5 mm.

The above description is only a preferred embodiment of the present application and should not be taken as limiting the present application, and any modifications, equivalents, improvements and the like that are made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. A process and a slicing method for forming a suspension structure through metal 3D printing are characterized by comprising the following steps:

according to the preset printing layer thickness, carrying out layered slicing on a part model corresponding to a target part by using slicing software to obtain a multilayer slice corresponding to the part model;

based on the multilayer slices, acquiring the size change dx of the adjacent upper-layer slices and lower-layer slices in the X direction and the size change dy in the Y direction in the coordinate axis;

if dx and dy are both less than or equal to zero, 3D printing the target part in an unsupported mode;

if dx and dy are both larger than zero, judging whether dx and dy are both larger than a, and if dx and dy are both larger than a, adopting a support adding mode to 3D print the target part; wherein a is the corresponding maximum overhanging length of different printing materials under the unsupported printing condition;

if dx and dy are both smaller than a, judging whether dx and dy are both larger than zero and smaller than a/2, if 0-dx-Once a/2 and 0-dy-Once a/2 are judged, adopting a transition-area-free slice scanning strategy, and scanning according to preset scanning parameters to obtain a scanning path filling strategy; if judging that the a/2-plus-dx-plus-a and the a/2-dy-plus-a are included, adopting a transition region slice scanning strategy, and adjusting preset scanning parameters in the transition region and outside the transition region for scanning according to the principle that the laser energy input density outside the transition region is less than the laser energy input density in the transition region is less than the laser energy input density of the part main body so as to obtain a scanning path filling strategy;

printing the target part based on the contour scan path filling strategy.

2. The forming process and slicing method for metal 3D printing suspension structure according to claim 1, wherein the scanning with the transition-area-free slicing scanning strategy according to preset scanning parameters to obtain the scanning path filling strategy comprises:

determining the highlighted cross section to occur in the nth layer of slice, wherein n is the number of layers of slices in the upper layer in the two adjacent layers of slices with dx and dy being larger than zero, and the highlighted cross section is the cross section part consisting of dx and dy in the two adjacent layers of slices with dx and dy being larger than zero;

taking the nth layer of slices as a boundary, rotating the slices of 1 to n-1 layers layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of 1 to n-1 layers; wherein the preset angle alpha is 25-40 degrees;

and scanning and filling the slices behind the n layers in a mode of alternately changing the scanning angle in the direction from the original section to the highlighted section, and maintaining the preset scanning parameters for scanning and filling when no transition region exists, so as to obtain a contour scanning path filling strategy behind the n layers.

3. The forming process and slicing method for metal 3D printing suspension structure according to claim 1, wherein the step of scanning with the transition region slicing scanning strategy is performed by adjusting preset scanning parameters in the transition region and outside the transition region according to the principle that the laser energy input density outside the transition region < the laser energy input density in the transition region < the laser energy input density of the part body, so as to obtain the scanning path filling strategy comprises:

determining the highlighted cross section to occur in the nth layer of slices, wherein n is the number of layers where the upper layer of slices are located in the two adjacent layers of slices which satisfy that dx and dy are both greater than zero, and the highlighted cross section is a cross section part consisting of dx and dy in the two adjacent layers of slices which satisfy that dx and dy are both greater than zero;

taking the nth layer of slices as a boundary, rotating the slices of 1 to n-1 layers layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of 1 to n-1 layers, wherein the preset angle alpha is 25-40 degrees;

scanning and filling the n-layer to n + (50-100) layer slices in a mode of alternately changing scanning angles in the direction from the original section to the highlighted section, determining the range of the transition region when the transition region exists, adjusting preset scanning parameters, and scanning and filling according to the fact that the laser energy input density of the transition region is larger than the laser energy input density outside the transition region to obtain a contour scanning path filling strategy from the n-layer to the n + (50-100) layer;

and clearing the transition region after the n + (50-100) layers, rotating layer by layer according to a preset angle alpha, and scanning and filling by using preset scanning parameters to obtain a contour scanning path filling strategy of all slices after the n + (50-100) layers.

4. The forming process and slicing method of metal 3D printing overhang structure according to any one of claims 2 or 3, wherein the n-layer to n + (50-100) layer slices are scan-filled in a manner of alternating scan angles in a direction from an original section to a highlighted section, and the method comprises the following steps:

in any two adjacent layers of slices, the scanning path of the upper layer of slices and the scanning path of the lower layer of slices form an included angle beta;

wherein beta is 30-40 degrees.

5. The process of forming and slicing a metal 3D printed overhang structure of claim 4, wherein said included angle β is 35 °.

6. A forming process and dicing method for a metal 3D printing overhang structure according to any one of claims 2 or 3, the preset scan parameters including scan pitch, laser power, and scan speed.

7. The process of forming and slicing a metal 3D printed overhang structure of claim 3, wherein said determining said transition zone extent comprises:

taking the intersecting contour line of the highlighted section and the original section as the inner contour line of the transition area;

acquiring a midpoint coordinate (X1, Y1) and two intersecting endpoint coordinates (X2, Y2) of an inner contour line of the transition region;

extending the midpoint coordinates (X1, Y1) by 6-7 units along the X-direction highlighted section to obtain the coordinates of the farthest corner points of the transition area;

smoothly connecting three points determined by the coordinates of the farthest corner point and the coordinates of the two intersected end points by using an arc line to form an outer contour line of the transition region;

the transition area range is defined by the area formed by the outer contour line and the inner contour line.

8. The process of forming and slicing a metal 3D printed overhang structure of claim 3, wherein determining the transition zone extent comprises:

acquiring the area of the highlighted section;

acquiring two intersection end points of an inner contour line and an outer contour line of the highlighted section;

and the area of the prominent section is divided equally by using a smooth dividing line, the area between the inner contour line and the dividing line is the transition area range, and the end points of the two ends of the dividing line are superposed with the two intersected end points of the inner contour line and the outer contour line.

9. The forming process and slicing method for the metal 3D printing suspension structure according to claim 1, wherein the step of slicing a part model corresponding to a target part by slicing software according to a preset printing layer thickness to obtain a multilayer slice corresponding to the part model comprises the following steps:

adjusting the placing position of the part model, wherein the placing requirement of the part is to avoid the phenomenon of reverse scraping in the printing process;

and importing the adjusted part model into slicing software, setting parameters of the slicing software, and finishing layered slicing of the part model through the slicing software.

10. The forming process and slicing method of a metal 3D printing overhang structure according to claim 1, wherein obtaining a dimension change dx in an X direction and a dimension change dy in a Y direction in a coordinate axis of adjacent upper and lower slices based on the multi-layer slices comprises:

marking the coordinate values of each layer of slices in the X and Y directions corresponding to each angular point by using slice software;

and subtracting the coordinate value of the adjacent lower slice from the coordinate value of the upper slice to obtain the dimension change amount dx and dy.

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