CN109262110B - Metal electric arc additive manufacturing method - Google Patents
Metal electric arc additive manufacturing method Download PDFInfo
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- CN109262110B CN109262110B CN201811405276.2A CN201811405276A CN109262110B CN 109262110 B CN109262110 B CN 109262110B CN 201811405276 A CN201811405276 A CN 201811405276A CN 109262110 B CN109262110 B CN 109262110B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/04—Welding for other purposes than joining, e.g. built-up welding
- B23K9/044—Built-up welding on three-dimensional surfaces
Abstract
The invention discloses a metal arc additive manufacturing method, which comprises the following steps: step 1, modeling a workpiece to be printed, determining the height of each layer of additive layer to be Hp according to the material performance of the workpiece, and performing layered slicing on a part digital model in the Z direction according to the layer height Hp by using arc additive slicing software; step 2, the robot executes the material adding path code in the step 1 to add materials; step 3, after the additive manufacturing in the step 2 is finished, scanning the surface of the additive product through laser, obtaining the height H of actual additive manufacturing by using an image processing algorithm, obtaining the number N of layers which are already added currently from a slicing module, calculating H2 to be H/N, obtaining the average layer height of each layer during the additive manufacturing in the step 2, re-slicing the model according to the layer height H2 at the position of the height H of the part model according to the height H of the actual additive manufacturing and the average layer height H2, and outputting an additive manufacturing program of the next N layers; and 4, repeating the steps 2-3 until the material increase of the part is finished.
Description
Technical Field
The invention relates to a metal arc additive manufacturing method, in particular to a method for improving metal arc additive manufacturing precision through laser tracking, and belongs to the technical field of metal welding processing.
Background
The electric arc additive manufacturing is a manufacturing method for realizing the forming of a workpiece by welding, melting and stacking metal layer by layer. In the traditional arc additive manufacturing step, slicing and path planning are generally performed on a digital model of a part through slicing software, and an additive manufacturing program is output at one time, and the additive manufacturing program is not adjusted in the additive manufacturing process. Because the welding process is influenced by many factors, the layer height difference at different temperatures is large, and under the condition that the material increase procedure is fixed, the errors in the height direction can be superposed layer by layer, and the larger the size of the manufactured part is, the larger the errors in the height direction are, but the errors in the height direction cannot be eliminated by carrying out secondary processing on the material increased part, so that the traditional electric arc material increase mode has a large defect in the aspect of precision. According to the invention, the actual height data of the part is acquired and fed back in a mode of line structure light scanning and slicing program layered output, and the material increase program is automatically corrected through software operation, so that the superposition of errors of each layer can be avoided, and the accuracy of electric arc material increase is greatly improved.
For the additive manufacturing process of large metal components, due to the fact that the number of additive layers is large, superposition errors are large, and the existing arc additive manufacturing method cannot meet the precision requirement of workpieces. Therefore, the development of a high-precision metal arc additive manufacturing method is necessary.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of providing a high-precision metal arc additive manufacturing method, which can calculate the actual additive height of a part and adjust the initial position of subsequent additive and the layer height of slice layering through the actual additive height, so that the precision of metal arc additive manufacturing is greatly improved.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a metal arc additive manufacturing method specifically comprises the following steps:
step 1, modeling a workpiece to be printed, determining the height of each layer of additive layer as Hp according to the material performance of the workpiece, performing layered slicing on a part digital model in a Z direction by using arc additive slicing software according to the layer height Hp to obtain a two-dimensional profile map of the part model, and generating an additive path by using a bias algorithm or a parallel line scanning algorithm; the layer height Hp of the part model is determined by the material performance of the workpiece according to the layering slicing basis of the part model at the initial time, for example, the additive layer height Hp is 2mm for the A material, and the additive layer height Hp is 3mm for the B material;
step 2, the robot executes the material adding path code in the step 1 to add materials; an additive layer or a continuous additive N layer;
step 3, after the additive manufacturing in the step 2 is finished, scanning the surface of the additive product through line laser, obtaining the height H of an actual additive by utilizing height range filtering and contour filtering, and if only one layer of additive is added in the step 2, namely N is 1, re-slicing the model according to the layer height H at the position of the height H of the part model, and outputting an additive manufacturing program of the lower N layers; if several layers are continuously added in the step 2, namely N is larger than 1, obtaining the number N of the layers which are added currently from the slicing module, calculating H2 to be H/N, obtaining the average layer height of each layer during material adding in the step 2, re-slicing the model according to the layer height H2 at the position of the height H of the part model according to the actual material adding height H and the average layer height H2, and outputting a material adding program of the next N layers;
and 4, repeating the steps 2-3 until the material increase of the part is finished.
In the step 1, after the arc additive slicing software slices the part digital model in layers, an additive path is generated by using a bias algorithm or a parallel line scanning algorithm, and additive path codes of one additive layer at a time or additive path codes of N additive layers at a time can be set.
In the step 2, the N value is set according to needs, the smaller the N value is, the higher the material increase precision is, and the larger the N value is, the higher the material increase efficiency is.
And 3, when the actual additive height H is obtained through calculation, recording an abnormal area with the difference of +/-1 mm from H, adjusting the additive process of the recorded abnormal area when the additive program of the lower N layers is output, increasing the printing speed of the convex part, reducing the wire feeding speed and the like, reducing the printing speed or increasing the wire feeding speed of the concave part, and performing subsequent additive by using the optimized program.
Wherein, in step 3, the height range filtering means: after N layers of materials are added, the current theoretical layer height is Hn (Hp N Hn), printed parts are scanned through line laser, point cloud data of the upper surfaces of the parts are obtained, first filtering is carried out on the point cloud data according to a set effective measurement height range Hv, and only points with the Z value meeting the condition that Hn-Hv is less than Z and Hn + Hv are reserved.
Wherein, contour filtering means: and acquiring the outline polygon of the slice of the Nth layer by slice software, traversing the point in the point cloud, projecting the point to an XY plane, and excluding the point if the point is positioned outside the slice outline.
The method for filtering the noise points comprises the following steps: firstly, setting an effective height Hv, traversing all points in the point cloud by knowing a current measuring point and a theoretical slice height Hs, and excluding points with the height z smaller than Hs-Hv and points with the height greater than Hs + Hv; and then judging whether the point in the point cloud is in the polygon obtained by slicing, then excluding all points outside the polygon, calculating whether the point is positioned in the polygon by using a ray method, and after excluding noise points, calculating the average Z value in the point cloud to be Hr, wherein the Hr is the actual printing layer height-material increase actual height H.
According to the noise point filtering method, the actual printing height is the average height of the filtered point cloud, and the average layer height is the actual printing height/the number of printed layers. After the actual printing height is obtained, the next layer of slice height is the actual height + the average layer height. The judgment basis of material increase completion is that the actual material increase height is 1-3mm greater than the height in the digital analogy, and the machining allowance is reserved.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
the method provided by the invention changes the mode that the traditional additive manufacturing outputs all additive programs at one time into layered output, acquires the actual additive height data of the part through line structured light scanning, and automatically corrects the subsequent additive program through software operation, thereby avoiding the problem of low overall precision of the part caused by layer-by-layer superposition of errors in the traditional additive manufacturing, and improving the precision of electric arc additive manufacturing. The method can calculate the actual additive height after each additive program is finished, and adjusts the initial position of subsequent additive and the slice layering layer height through the actual additive height, so that the metal arc additive manufacturing precision is greatly improved.
Drawings
FIG. 1 shows that after N layers of materials are added, printed parts are scanned by line laser to obtain point cloud data of the upper surfaces of the parts;
FIG. 2 is a plot of the height range filtered and contour filtered point cloud data;
FIG. 3 shows the height of the surface of the point cloud, i.e., the actual additive layer height obtained by calculating the average height of the point cloud after the effective points are obtained;
FIG. 4 is a flow chart of the method of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
As shown in fig. 4, the metal arc additive manufacturing method of the present invention specifically includes the following steps:
step 1, a process experiment can obtain a weld width and height value Hw (Hw is an empirical value obtained according to process experiment data) of a specific welding wire under the conditions of a certain temperature, a welding speed, a wire feeding speed and the like, software slices a part digital-analog STL file according to Hw in the Z direction to obtain a two-dimensional contour map, then a material adding path is generated by using a bias algorithm or a parallel line scanning algorithm, and the software can select to output a plurality of layers of slicing paths at one time;
step 2, the robot executes the additive code;
step 3, after adding N layers, scanning and printing the part through line laser to obtain point cloud data of the upper surface of the part, wherein the current theoretical layer height is Hn;
step 4, according to the set effective measurement height range Hv, carrying out first filtering on point cloud data, and only keeping points in which the Z value (height to) in the point cloud meets the condition that Hn-Hv is more than Z and less than Hn + Hv;
step 5, obtaining the profile polygon of the slice at the Nth layer by slice software, traversing points in the point cloud, projecting the points to an XY plane, and if the points are positioned outside the slice profile, excluding the points; (ray method can be used to calculate whether a point is inside a polygon)
Step 6, after noise points are eliminated through height range and contour filtering, calculating the average Z value in the point cloud as Hr, wherein the average Z value is the actual layer height after N layers are printed, and the current average layer height Ha can be obtained through the actual layer height Hr; ha is Hr/N;
and 7, re-slicing by using the actual printing layer height Hr and the new average layer height Ha (at the moment, the starting position of slicing is the position of the height Hr of the part model, and the layer height of layered slicing is Ha), and acquiring next path codes of a plurality of layers for material increase.
Through a printing-laser measurement-result feedback correction mechanism, the accumulated error caused by continuous change of the layer height in the electric arc material increase process can be controlled, the dry elongation is adjusted without manual intervention in the material increase process, and the total height of the part can also meet the expected processing standard.
Example 1
The invention relates to a metal arc additive manufacturing method, which specifically comprises the following steps:
step 1, modeling a workpiece to be printed, obtaining the height Hp of each additive layer according to the material performance (material: 4043, diameter: 1.2, wire feeding speed: 5.5m/min) of the workpiece (Hp is 2.8mm which is an empirical value obtained according to the process), and slicing the part digital model in a Z direction in a layered mode according to the layer height Hp by using electric arc additive slicing software to obtain a two-dimensional profile map; generating an additive path by using a parallel line scanning algorithm, and setting an additive path code of one additive layer at a time;
step 2, the robot executes the material adding path code in the step 1 to add materials;
step 3, after the additive manufacturing in the step 2 is finished, scanning the surface of the additive product through laser, obtaining the height H of the actual additive by utilizing height range filtering and contour filtering, re-slicing the model according to the layer height H at the position of the height H of the part model, and outputting the additive manufacturing program of the next layer;
and 4, repeating the operations in the steps 2-3, namely scanning once every time when the material is added to one layer, calculating the height of each actual material addition, and then slicing the model again according to the height of the actual material addition at the position of the corresponding height of the part model until the material addition of the part is finished.
Example 2
The invention relates to a metal arc additive manufacturing method, which specifically comprises the following steps:
step 1, modeling a workpiece to be printed, determining the height of each additive layer to be Hp (3.2mm) according to the material performance of the workpiece (material: 4043 diameter: 1.2, wire feeding speed: 7.5m/min), and slicing the digital-to-analog layer height Hp of the part in a Z direction by electric arc additive slicing software to obtain a two-dimensional profile map; generating an additive path by using a parallel line scanning algorithm, and setting additive path codes of a plurality of additive layers (N & gt 1) at one time;
step 2, the robot executes the material adding path code in the step 1 to add materials; namely, a continuous additive multilayer;
step 3, after the additive manufacturing in the step 2 is finished, scanning the surface of the additive product through laser, obtaining the height H of an actual additive by utilizing height range filtering and contour filtering, obtaining the number N of layers which are added currently from a slicing module, calculating H2 to be H/N, obtaining the average layer height during additive manufacturing, re-slicing the model according to the layer height H2 at the position of the height H of the part model, and outputting an additive manufacturing program of the next N layers;
and 4, repeating the operations in the steps 2-3, namely after each material increase procedure is completed (every material increase N layers), scanning once, calculating the actual material increase height after each material increase procedure is completed, calculating the average layer height of each layer during material increase, and then re-slicing the model according to the height of the average layer height at the position of the corresponding height of the part model until the material increase of the part is completed. The number of additive layers in the last round may be smaller than N (smaller than the number of layers set by each additive program), the actual number of additive layers needs to be calculated according to the remaining additive amount in the last round, the height of the part after additive finishing is 1-3mm larger than that of the part in the digital model, and machining allowance is reserved.
The height Hp of the primary layering slice is obtained through process experimental data, the average layer height can be obtained through measurement in the subsequent steps, the experimental data are corrected, errors in the XY direction of the part cannot be accumulated, the errors are smaller than 3mm, the quality of the final part cannot be influenced, but the errors in the Z direction can be accumulated, the errors are large, and the requirement of design tolerance cannot be met.
Claims (3)
1. A metal arc additive manufacturing method is characterized by comprising the following steps:
step 1, modeling a workpiece to be printed, determining the height of each layer of additive layer as Hp according to the material performance of the workpiece, performing layered slicing on a part digital model in the Z direction by using arc additive slicing software according to the layer height Hp to obtain a two-dimensional profile of the part model, and generating an additive path by using a bias algorithm or a parallel line scanning algorithm;
step 2, the robot executes the material adding path code in the step 1 to add materials; an additive layer or a continuous additive N layer;
step 3, after the additive manufacturing in the step 2 is finished, scanning the surface of the additive manufactured product through line laser, obtaining the height H of the actual additive by utilizing height range filtering and contour filtering, and if only one layer of additive is added in the step 2, namely N is 1, re-slicing the model according to the layer height H at the position of the height H of the part model, and outputting an additive manufacturing program of the lower N layers; if several layers are continuously added in the step 2, namely N is larger than 1, obtaining the number N of the layers which are added currently from the slicing module, calculating H2 to be H/N, obtaining the average layer height of each layer during material adding in the step 2, re-slicing the model according to the layer height H2 at the position of the height H of the part model according to the actual material adding height H and the average layer height H2, and outputting a material adding program of the next N layers; wherein, the height range filtering means: after the N layers of materials are added, the current theoretical layer height is Hn, printed parts are scanned through line laser, point cloud data on the upper surfaces of the parts are obtained, the point cloud data are filtered for the first time according to the set effective measurement height range Hv, and only points with the Z value meeting the condition that Hn-Hv is more than Z and Hn + Hv are reserved in the point cloud; contour filtering means: acquiring a contour polygon of an Nth layer of slices by slice software, traversing points in the point cloud, projecting the points to an XY plane, and if the points are positioned outside the slice contour, excluding the points;
and 4, repeating the steps 2-3 until the material increase of the part is finished.
2. The metal arc additive manufacturing method of claim 1, wherein: in the step 1, after the arc additive slicing software slices the part digital model in layers, an additive path is generated by using a bias algorithm or a parallel line scanning algorithm, and additive path codes of one additive layer at a time or additive path codes of N additive layers at a time can be set.
3. The metal arc additive manufacturing method of claim 2, wherein: the N value is set according to needs, the smaller the N value is, the higher the material increase precision is, the larger the N value is, and the higher the material increase efficiency is.
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| JP6765569B1 (en) * | 2019-08-07 | 2020-10-07 | 三菱電機株式会社 | Laminated modeling equipment, laminated modeling method, and laminated modeling program |
| CN112439971B (en) * | 2019-08-28 | 2022-08-16 | 南京理工大学 | Continuous electric arc additive manufacturing method and device of self-adaptive non-flat surface |
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