CN103366069A - Hierarchical algorithm of selective laser sintering - Google Patents
Hierarchical algorithm of selective laser sintering Download PDFInfo
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- CN103366069A CN103366069A CN2013103272179A CN201310327217A CN103366069A CN 103366069 A CN103366069 A CN 103366069A CN 2013103272179 A CN2013103272179 A CN 2013103272179A CN 201310327217 A CN201310327217 A CN 201310327217A CN 103366069 A CN103366069 A CN 103366069A
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Abstract
The invention provides a hierarchical algorithm of selective laser sintering, which is used for establishing a precise product model. A method comprises the following steps: (1) reading and displaying an STL file; (2) locally encrypting an STL model; (3) selecting a layered slice plane; (4) sorting the layered slice plane; (5) compensating a positive and negative error; and (6) outputting a model. According to the hierarchical algorithm, through establishing a dynamic facet table for different tangent planes, the usage mount of a memory is lowered, time required by topological information is reduced, and the efficiency of hierarchical processing is improved; and meanwhile, through the method of locally encrypting the model and compensating the positive and negative error, the precision of the model is greatly increased, and a strong technical support is provided for the improvement of the precision of part manufacturing.
Description
Technical field
The invention belongs to Laser Processing rapid shaping field, be specifically related to a kind of hierarchical algorithm of selective laser sintering.
Background technology
Along with the widespread use of the rapidly general and CAD/CAM technology of computer technology, product develops on a large scale to making to have had very from design model, and the construction cycle of product, production cycle, update cycle are shorter and shorter.Therefore, in the face of rapid a variation and unforeseen buyer's market, traditional production in enormous quantities pattern just seemed more and more slower and passive to the response in market in the past.The fast responding market demand, oneself becomes the important trend of development of manufacturing, and rapid prototyping technology grows up under fast responding market and the background of meeting consumers' demand.And be widely used in the fields such as machinery, material, electronics, medical science.But in the processing procedure that rapid shaping is made, because there is wedge angle in the STL model, the features such as concave surface or flat horizontal surface badly influence the precision of the mechanical component of processing.
In order to address the above problem, the hierarchical algorithm that adopts at present has: adaptive layered, become bed thickness technology, positive and negative error compensation etc.
1, adaptive layered algorithm.The adaptive layered algorithm can adopt different lift heights according to the difference that surface accuracy to be processed requires, and when guaranteeing the surface profile precision, reduces the layering number of plies, improves the efficient of Laser Processing.Because the quantity of STL model tri patch is very large, simple in structure based on the hierarchical algorithm of tri patch topology information other algorithm data of comparing, the mutual relationship between the tri patch be can fully represent, calculating and the processing of follow-up profile Data Node data are convenient to.It is a certain cross section conduct minute layer cross section between above layer cross section and the lower layer cross section, and make this layer sign solid object surface roughness δ or characterize volumetric errors S minimum, when not reducing layering manufacturing efficient, reduced to greatest extent layering and made original reason error.
2, become the bed thickness algorithm.Becoming the bed thickness technology mainly is the redundant node data of deletion, then according to when the data of front profile layer, calculate the lift height of lower one deck, so that lift height changes with the variation of every layer data, reduce to greatest extent the number of plies of layering, thereby improve the efficient of whole Slicing Algorithm.
3, positive and negative error compensation.Positive and negative error compensation is the difference according to the forming direction of part, after the printing, can make part occur that local volume increases and local volume reduces two kinds of situations, in order to satisfy part requirement in actual applications, two kinds of situations for volume change propose two kinds of solutions, a kind of is the positive error compensation, and another kind is the negative error compensation.
For above-mentioned algorithm, all there is certain defective, adaptive algorithm and change bed thickness algorithm do not satisfy positive and negative compensation of error, and the local increase to volume of part that positive and negative compensation of error can only be single reduces compensation, can not satisfy the precision of section.
Summary of the invention
In order to overcome the shortcoming of above-mentioned prior art existence, a kind of hierarchical algorithm of selective laser sintering is provided, solved the problem that existing algorithm section precision and error compensation can not be taken into account.
In order to address the above problem, the present invention by the following technical solutions: a kind of hierarchical algorithm of selective laser sintering, be used for setting up accurate product model, it is characterized in that, described algorithm may further comprise the steps:
Step 1: read in and show stl file;
The local refinement of step 2:STL model;
Step 3: choose the hierarchy slicing plane;
Step 4: hierarchy slicing plane ordering;
Step 5: positive and negative error compensation;
Step 6: output model.
Further, described step 1 may further comprise the steps:
Detect the stl file form;
The tri patch information of memory model;
Read tri patch information;
Preserve tri patch information;
Show stl file.
Further, described tri patch information comprises: the sum of tri patch, the normal vector of tri patch, three summits and three limits.
Further, described step 2 may further comprise the steps:
Convex and concave feature according to angle criterion and Gradient Criterion judgment models;
According to the method phase vector of tri patch and the positive and negative checking of carrying out feature of amassing C of moulding vector;
The position that needs are encrypted is encrypted processing.
Further, described step 3 may further comprise the steps:
Set up the set of STL model triangle surface;
Coordinate figure according to Z-direction carries out packet sequencing from small to large;
Set the distance values between the hierarchy slicing plane;
Ask layered plane and triangle surface along the intersection section of Z-direction;
Form the triangular mesh dough sheet table that intersects with current layered plane.
Further, for the profile with convex and concave feature, the criterion of positive and negative error compensation is in the described step 5:
If C=0, the cross section intersection point on the Z axis just drops on the desirable outline line;
If C＜0 produces positive error;
If C〉0, produce negative error;
Wherein, C is that a certain triangle surface normal vector ξ and moulding vector Z are long-pending.
Further, for the profile of flat features, the criterion of positive and negative error compensation is in the described step 5:
If C=1 illustrates that triangle normal vector ξ is identical with moulding vector Z direction;
If C=-1 illustrates triangle normal vector ξ and moulding vector Z opposite direction;
Wherein, C is that a certain triangle surface normal vector ξ and moulding vector Z are long-pending.
The invention has the beneficial effects as follows: the present invention is by setting up dynamic dough sheet table to different sections, reduced the internal memory use amount, reduced the required time of topology information, improved the layering treatment effeciency, simultaneously, the present invention has improved the precision of model greatly by the method for model local refinement and positive and negative error compensation, for the raising of part processing precision provides strong technical support.
Description of drawings
The present invention is described further below in conjunction with drawings and Examples:
Fig. 1 is process flow diagram of the present invention.
Embodiment
As shown in Figure 1, the hierarchical algorithm of a kind of selective laser sintering of the present invention is used for setting up accurate product model, may further comprise the steps:
Step 1: read in and show stl file.Because stl file has ASCII and two kinds of storage formats of scale-of-two, therefore at first concordance file carries out format detection, and calculates the triangle surface information of model, then reads and preserve triangle surface information, after finishing data and reading, the related function that calls Directx11 shows.Wherein, the information of tri patch comprises: the normal vector of tri patch, three summits and three limits.
The local refinement of step 2:STL model.At first, according to the convex and concave feature of angle criterion and Gradient Criterion judgment models, then according to the method phase vector of tri patch and the positive and negative checking of carrying out feature of amassing C of moulding vector, the position of at last needs being encrypted is encrypted processing.
Illustrate: read in a data point as profile starting point P
0, seek in the counterclockwise direction the 2nd some P
1, make up line segment P
0P
1, in like manner construct P
1P
2, calculate the angle theta of two line segments, satisfy following formula such as angle:
θ=nπ/2 （n=0,1，……j）
P herein is described
0P
1With P
1P
2Vertical or the conllinear of two segmented line need not be encrypted herein, if do not satisfy following formula, illustrates to have certain angle between two end lines, just need to encrypt it.
After judging the feature of angle variation, then according to the method phase vector of tri patch and the positive and negative checking of carrying out feature of amassing C of moulding vector, negative if the C value is just becoming, illustrate it is concave contour herein, if the C value is just being become by negative, illustrate it is cam contour herein, need local refinement herein.
Step 3: choose the hierarchy slicing plane.The hierarchy slicing plane is the plane of intersecting with certain spacing and STL model when hierarchy slicing, and the criterion of choosing is:
(a) triangular mesh dough sheet span on fabrication orientation is larger, and the section of then intersecting with it is more;
(b) cut the Z of triangular mesh dough sheet by the Z change in coordinate axis direction
MinFar away apart from initial section, after more leaning on when trying to achieve the slicing profile line.
The process of choosing is: STL model triangle surface is set up the dough sheet set, coordinate figure according to Z-direction carries out packet sequencing from small to large, get certain coordinate figure interval as the spacing between the hierarchy slicing plane, layered plane and triangle surface are intersected along Z-direction, ask the intersection section.After asking friendship, original triangle surface may lose triangle information representing, in order to improve the efficient of layering, need to be in the layering processing procedure, and the dynamic triangular mesh dough sheet table that intersects with current layered plane that forms.When the section moves to lower one deck, analyze first dynamic dough sheet table, with disjoint patch grids deletion, to join in the dynamic dough sheet table with the new triangular mesh dough sheet that intersect in this section simultaneously, set up the topology information of local triangle's patch grids, ask the computing of intersection section, obtain cross section contour, until layering finishes.
Step 4: hierarchy slicing plane ordering.The factor that affects STL grid model layering treatment effeciency mainly contains three: (a) judgement of section and triangular mesh dough sheet position relationship; (b) calculating of section and triangular mesh dough sheet intersection section; (c) output of cross section contour.If improving the efficient of layering needs layered plane is sorted.
According to the feature of choosing the Slice by slice cutting plane and having, if N section arranged, then the triangular mesh dough sheet is divided into the N group, to be placed in same group with the triangular mesh dough sheet that intersect in same section, guarantee when carrying out a certain slicing delamination, the computing of intersection section is asked in the triangular mesh dough sheet participation of only intersecting with this section, and then has reduced the judgement of triangular mesh dough sheet and section position relationship, has improved layering efficient.
Step 5: positive and negative error compensation hierarchy slicing has two kinds of hierarchy slicing molding modes with the Z-direction section, and a kind of is top-down, and another kind is bottom-up.No matter be which kind of mode, because between cutting layered sliced surfaces, have spacing, all will make part produce local volume increase or loss phenomenon, i.e. positive and negative error.This part error is owing to the factors such as step effect, flat horizontal surface cause, thereby error compensation in addition during section.
Judge which partial volume which partial volume of forming part increases and reduces, and can utilize the C that mentions in the local refinement of STL model, C represents that a certain triangle surface normal vector ξ and moulding vector Z are and amasss, that is:
C=ξ·Z
For the concavo-convex profile under the molding mode from top to bottom, if C=0, the cross section intersection point on the Z axis just drops on the desirable outline line; If C＜0 produces positive error; If C〉0, produce negative error.
For the profile of the flat features under the molding mode from top to bottom, if C=1 illustrates that triangle normal vector ξ is identical with moulding vector Z direction; If C=-1 illustrates triangle normal vector ξ and moulding vector Z opposite direction.
Step 6: after finishing above-mentioned all operations were, just finished whole processing of model, the model output after processing is got final product.
The above is preferred implementation of the present invention, for those skilled in the art, under the prerequisite that does not break away from the principle of the invention, can also make some improvements and modifications, and these improvements and modifications also are regarded as protection scope of the present invention.
Claims (7)
1. the hierarchical algorithm of a selective laser sintering is used for setting up accurate product model, it is characterized in that, described algorithm may further comprise the steps:
Step 1: read in and show stl file;
The local refinement of step 2:STL model;
Step 3: choose the hierarchy slicing plane;
Step 4: hierarchy slicing plane ordering;
Step 5: positive and negative error compensation;
Step 6: output model.
2. the hierarchical algorithm of a kind of selective laser sintering according to claim 1 is characterized in that, described step 1 may further comprise the steps:
Detect the stl file form;
The tri patch information of memory model;
Read tri patch information;
Preserve tri patch information;
Show stl file.
3. the hierarchical algorithm of a kind of selective laser sintering according to claim 2 is characterized in that, described tri patch information comprises: the sum of tri patch, the normal vector of tri patch, three summits and three limits.
4. the hierarchical algorithm of a kind of selective laser sintering according to claim 1 is characterized in that, described step 2 may further comprise the steps:
Convex and concave feature according to angle criterion and Gradient Criterion judgment models;
According to the method phase vector of tri patch and the positive and negative checking of carrying out feature of amassing C of moulding vector;
The position that needs are encrypted is encrypted processing.
5. the hierarchical algorithm of a kind of selective laser sintering according to claim 1 is characterized in that, described step 3 may further comprise the steps:
Set up the set of STL model triangle surface;
Coordinate figure according to Z-direction carries out packet sequencing from small to large;
Set the distance values between the hierarchy slicing plane;
Ask layered plane and triangle surface along the intersection section of Z-direction;
Form the triangular mesh dough sheet table that intersects with current layered plane.
6. the hierarchical algorithm of a kind of selective laser sintering according to claim 1 is characterized in that, for the concavo-convex contour feature under the molding mode from top to bottom, the criterion of positive and negative error compensation is in the described step 5:
If C=0, the cross section intersection point on the Z axis just drops on the desirable outline line;
If C＜0 produces positive error;
If C〉0, produce negative error;
Wherein, C is that a certain triangle surface normal vector ξ and moulding vector Z are long-pending.
7. the hierarchical algorithm of a kind of selective laser sintering according to claim 1 is characterized in that, for the flat profile feature under the molding mode from top to bottom, the criterion of positive and negative error compensation is in the described step 5:
If C=1 illustrates that triangle normal vector ξ is identical with moulding vector Z direction;
If C=-1 illustrates triangle normal vector ξ and moulding vector Z opposite direction;
Wherein, C is that a certain triangle surface normal vector ξ and moulding vector Z are long-pending.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103934569A (en) * | 2014-04-28 | 2014-07-23 | 南京先进激光技术研究院 | Layered slicing method based on selective laser sintering |
| CN104504186A (en) * | 2014-12-10 | 2015-04-08 | 广州中国科学院先进技术研究所 | Implementation method based on 3D (Three Dimensional) printing data processing software platform |
| CN104503711A (en) * | 2014-11-17 | 2015-04-08 | 杭州先临三维科技股份有限公司 | Self-adaption layering method of 3D printing |
| CN104644276A (en) * | 2013-11-22 | 2015-05-27 | 无锡时代天使医疗器械科技有限公司 | Method for manufacturing teeth correcting equipment and teeth correcting equipment |
| CN105398056A (en) * | 2015-12-03 | 2016-03-16 | 天津大学 | Self-adaptive hierarchical algorithm for 3D (three-dimensional) printing |
| CN103970949B (en) * | 2014-05-05 | 2017-04-05 | 华侨大学 | A kind of rapid shaping intermediate cam patch model by side layered approach |
| CN111324955A (en) * | 2020-02-19 | 2020-06-23 | 北京工业大学 | Free-form surface laser cutting method |
| CN113414987A (en) * | 2021-06-23 | 2021-09-21 | 哈尔滨理工大学 | 3D printing self-adaptive layering thickness method |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104644276A (en) * | 2013-11-22 | 2015-05-27 | 无锡时代天使医疗器械科技有限公司 | Method for manufacturing teeth correcting equipment and teeth correcting equipment |
| CN103934569A (en) * | 2014-04-28 | 2014-07-23 | 南京先进激光技术研究院 | Layered slicing method based on selective laser sintering |
| CN103934569B (en) * | 2014-04-28 | 2016-01-20 | 南京先进激光技术研究院 | A kind of hierarchical slicing method based on selective laser sintering |
| CN103970949B (en) * | 2014-05-05 | 2017-04-05 | 华侨大学 | A kind of rapid shaping intermediate cam patch model by side layered approach |
| CN104503711A (en) * | 2014-11-17 | 2015-04-08 | 杭州先临三维科技股份有限公司 | Self-adaption layering method of 3D printing |
| CN104503711B (en) * | 2014-11-17 | 2017-10-20 | 杭州先临三维科技股份有限公司 | A kind of adaptive layered method of 3D printing |
| CN104504186A (en) * | 2014-12-10 | 2015-04-08 | 广州中国科学院先进技术研究所 | Implementation method based on 3D (Three Dimensional) printing data processing software platform |
| CN104504186B (en) * | 2014-12-10 | 2017-10-31 | 广州中国科学院先进技术研究所 | A kind of implementation based on 3D printing data processing software platform |
| CN105398056A (en) * | 2015-12-03 | 2016-03-16 | 天津大学 | Self-adaptive hierarchical algorithm for 3D (three-dimensional) printing |
| CN111324955A (en) * | 2020-02-19 | 2020-06-23 | 北京工业大学 | Free-form surface laser cutting method |
| CN111324955B (en) * | 2020-02-19 | 2023-10-10 | 北京工业大学 | Free-form surface laser cutting processing method |
| CN113414987A (en) * | 2021-06-23 | 2021-09-21 | 哈尔滨理工大学 | 3D printing self-adaptive layering thickness method |
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Application publication date: 20131023 |