CN115401217B - Method for developing preheating process parameters of electron beam selective powder bed - Google Patents
Method for developing preheating process parameters of electron beam selective powder bed Download PDFInfo
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- CN115401217B CN115401217B CN202211232377.0A CN202211232377A CN115401217B CN 115401217 B CN115401217 B CN 115401217B CN 202211232377 A CN202211232377 A CN 202211232377A CN 115401217 B CN115401217 B CN 115401217B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention discloses a method for developing preheating process parameters of an electron beam selective powder bed, which is characterized by comprising the following steps of: the method comprises a cold powder experiment and a hot powder experiment, belongs to the technical field of powder bed preheating processes, can quickly find out optimal powder bed preheating parameters through the cold powder experiment and the hot powder experiment, can effectively reduce blowing powder in the actual printing and forming process, has practical value, can quickly find out the powder bed preheating parameters through the cold powder experiment and the hot powder experiment, realizes stable printing of electron beam selective melting of metal materials, quickly and accurately finds out the electron beam selective melting and forming preheating parameters, stably preheats and is not easy to blow powder in the actual printing process, can test dozens of groups of parameters through the cold powder experiment and the hot powder experiment, and can greatly reduce the experiment cost by finding out the parameters in a relatively short time, thereby improving the experiment efficiency.
Description
Technical Field
The invention belongs to the technical field of powder bed preheating processes, and particularly relates to a method for developing parameters of an electron beam selective powder bed preheating process.
Background
Along with the progress of science and technology, 3D printing technology is very widely applied in aerospace and biomedical fields, but refractory metals such as intermetallic compounds cannot be manufactured by adopting a traditional laser selective melting forming method, and most of the prior art adopts a traditional casting method at present, but the casting cost is higher, and the precision is poor. The electron beam selective melting forming has the advantages of high energy utilization rate, no reflection, high power density, high scanning speed, no pollution to vacuum environment, low residual stress and the like, is particularly suitable for directly forming active, refractory and brittle metal materials, and has wide application prospect in the fields of aerospace, biomedical treatment, automobiles, molds and the like. The main factor limiting the wide application of electron beam selective melting is the complex process, especially the preheating process of powder bed. The electron beam selected powder bed has more preheating parameters, all the parameters are mutually coupled, and the traditional comprehensive test method and the orthogonal method are adopted, so that the workload is large, and a large amount of manpower and material resources are consumed by the numerous parameters. And the traditional method is adopted to heat the substrate to the temperature required by the printed part, then the test parameters are started, the temperature rise of the substrate room to the high temperature required by printing generally takes 1 hour, a large amount of electric energy and time are consumed, powder can inhibit powder blowing under the high temperature condition, and the temperature of the preheating parameters for the test is reduced in the printing process, so that the risk of powder blowing can be reduced.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for developing the preheating technological parameters of the electron beam selective powder bed, which aims at overcoming the defects of the background technology, and can quickly find the preheating parameters of the powder bed through a cold and hot powder experiment to realize stable printing of electron beam selective melting of metal materials.
The invention adopts the following technical scheme for solving the technical problems:
the development method of the preheating technological parameters of the electron beam selective powder bed comprises a cold powder experiment and a hot powder experiment, and is used for quickly finding out the preheating parameters of the powder bed through the cold powder experiment and realizing stable printing of electron beam selective melting of metal materials; the cold powder experiment comprises the following steps:
step 1, preparing conditions: removing the thermocouple and the grounding wire, lowering the forming cylinder, adding enough powder into the forming cylinder, scraping the powder pile with a scraper, selecting a process file to be printed, and only keeping a preheating process without a MELT process;
step 2, finding a process forming window:
step 2.1, opening the high-voltage unit, directly clicking a start button of the equipment, not selecting a preheating substrate option, and starting powder bed preheating;
step 2.2, adjusting starting current, preheating average current, preheating scanning speed, preheating electron beam defocusing amount, preheating branching number and scanning line interval parameters;
step 2.3, when the powder blowing phenomenon occurs in the parameter changing process, the substrate is lowered by 1 millimeter, powder is manually taken out, the powder bed is scraped, and then the test is continued;
the hot powder experiment specifically comprises the following steps:
step A, equipment preparation: selecting a printing preparation device according to a normal electron beam;
step B, selecting a file: selecting a process file to be printed, and only reserving a preheating process without a MELT process;
step C, finding a process forming window:
step C1, preheating the powder on the powder bed according to the parameters found by a cold powder experiment after the substrate is preheated to 700-1150 ℃, observing whether the preheated powder bed has cracking phenomenon or not through an observation window, and increasing the preheating current if the powder bed has no cracking normally, and repeating the steps
Repeating times, scanning the speed parameter until the powder bed has cracks;
step C2, preheating parameters can be adjusted according to the printing condition in the subsequent printing process, and the adjustment parameters are not beyond a cold and hot powder experiment process window;
in the step 1, the forming cylinder descends for a certain distance of 40-50mm;
in step 2.2, during the preheating process, the preheating current starts from the minimum current, after the preset number of repetitions, the maximum current is maintained after the maximum current is increased, until the overall heat input reaches the preset average current level, until the three layers of preheating are not blown, and the optimal preheating parameters are found.
As a further preferable scheme of the method for developing the preheating process parameters of the electron beam selective powder bed, in the step C1, the parameter with cracks is the upper limit parameter of the preheating of the powder bed.
Compared with the prior art, the technical scheme provided by the invention has the following technical effects:
according to the invention, the optimal powder bed preheating parameters can be quickly found out through cold and hot powder experiments, and in the actual printing and forming process, the preheating parameters found out by the method can effectively reduce powder blowing, so that the method has practical value;
the preheating parameters of the powder bed are difficult to find when a certain metal material is subjected to selective melting printing by adopting the electron beam, and the preheating parameters of the powder bed can be quickly found through a cold and hot powder experiment, so that stable printing of selective melting of the metal material by adopting the electron beam is realized;
according to the invention, through an experimental method, the preheating parameters of electron beam selective melting forming are rapidly and accurately found, and the powder is stably preheated in the actual printing process and is not easy to blow;
according to the invention, tens of groups of parameters can be tested by one furnace through cold powder and hot powder tests, and the parameters can be found in a relatively short time, so that the test cost is greatly reduced, and the test efficiency is improved.
Drawings
The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
FIG. 1 is a flow chart of electron beam selective melting according to the present invention.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings:
the following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the electron beam selective melting flow diagram includes searching for powder preheating stability parameters and a solid printing process;
the method comprises a cold powder experiment and a hot powder experiment, wherein the method is used for quickly finding out the powder bed preheating parameters through the cold powder experiment and realizing stable printing of electron beam selective melting of metal materials;
according to the invention, the optimal powder bed preheating parameters can be quickly found out through cold and hot powder experiments, and in the actual printing and forming process, the preheating parameters found out by the method can effectively reduce powder blowing, so that the method has practical value; the preheating parameters of the powder bed are difficult to find when a certain metal material is subjected to selective melting printing by adopting the electron beam, and the preheating parameters of the powder bed can be quickly found through a cold and hot powder experiment, so that stable printing of selective melting of the metal material by adopting the electron beam is realized; according to the invention, through an experimental method, the preheating parameters of electron beam selective melting forming are rapidly and accurately found, and the powder is stably preheated in the actual printing process and is not easy to blow; according to the invention, tens of groups of parameters can be tested by one furnace through cold powder and hot powder tests, and the parameters can be found in a relatively short time, so that the test cost is greatly reduced, and the test efficiency is improved.
The cold powder experiment comprises the following steps:
step 1, preparing conditions: removing the thermocouple and the grounding wire, lowering the forming cylinder, adding enough powder into the forming cylinder, scraping the powder pile with a scraper, selecting a process file to be printed, and only keeping a preheating process without a MELT process; a certain distance of 40-50mm;
step 2, finding a process forming window:
step 2.1, opening the high-voltage unit, directly clicking a start button of the equipment, not selecting a preheating substrate option, and starting powder bed preheating;
and 2.2, adjusting parameters such as starting current, preheating average current, preheating scanning speed, preheating electron beam defocusing amount, preheating branching number, scanning line spacing and the like as shown in table 1. In the actual preheating process, the preheating current starts from the minimum current, after the preset repetition times, the maximum current is maintained after the maximum current is increased, until the whole heat input reaches the set average current level, and the optimal preheating parameters are found until the powder blowing does not occur in the three-layer preheating;
TABLE 1
| Parameter name | Focusing current | Minimum size | Electric current | Scanning speed | Number of lines | Line spacing |
| Numerical value | 20-100mA | 35-180mm | 1-30mA | 500-1200mm/s | 2-20 | 0.4-1.0mm |
Step 2.3, when the powder blowing phenomenon occurs in the parameter changing process, the substrate is lowered by 1 millimeter, powder is manually taken out, the powder bed is scraped, and then the test is continued;
the hot powder experiment specifically comprises the following steps:
step A, equipment preparation: selecting a printing preparation device according to a normal electron beam;
step B, selecting a file: selecting a process file to be printed, and only reserving a preheating process without a MELT process;
step C, finding a process forming window:
step C1, preheating the substrate to 700-1150 ℃, starting preheating the powder on the powder bed according to the parameters found by a cold powder experiment, observing whether the preheated powder bed has cracking phenomenon through an observation window, if the powder bed is normal and has no cracking, increasing preheating current, repeating times, and scanning speed parameters until the powder bed has cracks; the parameter at which the crack occurs is the upper limit parameter for preheating the powder bed.
And step C2, the preheating parameters can be adjusted according to the printing condition in the subsequent printing process, and the adjustment parameters are not beyond the cold and hot powder experiment process window.
The solid printing process comprises the steps of preheating a substrate, laying powder, preheating the powder, melting the solid and post-preheating, and is specifically shown in fig. 1.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A method for developing preheating process parameters of an electron beam selective powder bed is characterized by comprising the following steps of: the method comprises a cold powder experiment and a hot powder experiment, and is used for quickly finding out the preheating parameters of a powder bed through the cold powder experiment and realizing stable printing of electron beam selective melting of metal materials;
the cold powder experiment comprises the following steps:
step 1, preparing conditions: removing the thermocouple and the grounding wire, lowering the forming cylinder, adding enough powder into the forming cylinder, scraping the powder pile with a scraper, selecting a process file to be printed, and only keeping a preheating process without a MELT process;
step 2, finding a process forming window:
step 2.1, opening the high-voltage unit, directly clicking a start button of the equipment, not selecting a preheating substrate option, and starting powder bed preheating;
step 2.2, adjusting starting current, preheating average current, preheating scanning speed, preheating electron beam defocusing amount, preheating branching number and scanning line interval parameters;
step 2.3, when the powder blowing phenomenon occurs in the parameter changing process, the substrate is lowered by 1 millimeter, powder is manually taken out, the powder bed is scraped, and then the test is continued;
the hot powder experiment specifically comprises the following steps:
step A, equipment preparation: selecting a printing preparation device according to a normal electron beam;
step B, selecting a file: selecting a process file to be printed, and only reserving a preheating process without a MELT process;
step C, finding a process forming window:
step C1, after the substrate is preheated to 700-1150 ℃, starting to perform powder matching according to the parameters found by a cold powder experiment
Preheating powder on the bed, observing whether the preheated powder bed has cracking phenomenon through an observation window, if the powder bed does not crack normally, increasing preheating current, repeating times, and scanning speed parameters until the powder bed has cracks;
step C2, preheating parameters can be adjusted according to the printing condition in the subsequent printing process, and the adjustment parameters are not beyond a cold and hot powder experiment process window;
in the step 1, the forming cylinder descends for a certain distance of 40-50mm;
in step 2.2, during the preheating process, the preheating current starts from the minimum current, after the preset number of repetitions, the maximum current is maintained after the maximum current is increased, until the overall heat input reaches the preset average current level, until the three layers of preheating are not blown, and the optimal preheating parameters are found.
2. The method for developing the preheating process parameters of the electron beam selective powder bed according to claim 1, wherein the method comprises the following steps of: in step C1, the parameter at which the crack occurs is the upper limit parameter for preheating the powder bed.
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