阅读说明：本技术 改善电子束增材制造零件表面质量的工艺方法 (Process method for improving surface quality of electron beam additive manufacturing part ) 是由 刘永胜 卢东 吴旺 钟兵 刘芯宇 于 2020-11-26 设计创作，主要内容包括：本发明公开了一种工艺方法,尤其是公开了一种改善电子束增材制造零件表面质量的工艺方法,属于增材制造工艺技术领域。提供一种成本相对较低,无需再次进行加工的改善电子束增材制造零件表面质量的工艺方法。所述的工艺方法通过在增材制造的熔融工序对增加的辅材进行电子束熔融后形成的外轮廓上再次通过激光进行精确重熔,然后再进入增材制造的冷却工序进行制造来获得符合要求的零件表面质量,其中,精确重熔后的增材制造零件表面的粗糙度不超Ra12。(The invention discloses a process method, particularly discloses a process method for improving the surface quality of an electron beam additive manufacturing part, and belongs to the technical field of additive manufacturing processes. The process method for improving the surface quality of the electron beam additive manufacturing part is relatively low in cost and does not need to be processed again. The process method comprises the steps of carrying out precise remelting on an outer contour formed by electron beam melting on an added auxiliary material in the melting process of additive manufacturing through laser again, and then carrying out manufacturing in the cooling process of additive manufacturing to obtain the surface quality of parts meeting the requirements, wherein the roughness of the surface of the additive manufacturing parts after precise remelting does not exceed Ra 12.)

1. A process method for improving the surface quality of electron beam additive manufacturing parts is characterized in that: the process method comprises the steps of carrying out precise remelting on the outer contour formed by electron beam melting on the added auxiliary material in the melting process of additive manufacturing through laser again, then carrying out manufacturing in the cooling process of additive manufacturing to obtain the surface quality of parts meeting the requirements,

wherein the roughness of the surface of the precisely remelted additive manufactured part does not exceed Ra 12.

2. The process method for improving the surface quality of the electron beam additive manufactured part according to claim 1, wherein the process method comprises the following steps: the precise remelting is completed by laser emitted by a laser arranged beside a camera in a forming cavity of a powder bed type electron beam device.

3. The process method for improving the surface quality of the electron beam additive manufactured part according to the claim 1 or 2, characterized in that: the additive manufacturing also comprises a powder laying process and a preheating process, the parameters of each process are controlled according to the following requirements,

the thickness of the powder spreading layer in the powder spreading process is not more than 50 mu m, the preheating temperature in the preheating process is 730 ℃, the scanning speed in the melting printing process is 12000mm/s, the beam current is 5-30mA, and the laser power in the laser remelting process is 250W, the spot diameter is 100 mu m and the scanning speed is 1100 mm/s.

4. The process method for improving the surface quality of the electron beam additive manufactured part according to claim 3, wherein the process method comprises the following steps: the grain diameter of the alloy powder laid in the powder laying process is 45-105 μm.

5. The process method for improving the surface quality of the electron beam additive manufactured part according to claim 4, wherein the process method comprises the following steps: before preheating and printing, the powder spreading needs to be vacuumized, and the specific requirements are that,

the vacuum degree of the forming chamber should reach 2X 10-3mbar, and the vacuum degree of the electron gun should reach 7X 10-5 mbar.

6. The process method for improving the surface quality of the electron beam additive manufactured part according to claim 5, wherein the process method comprises the following steps: before vacuumizing, marking the center of the base plate on which the alloy powder is laid, leveling, vacuumizing the forming bin and the electron gun, starting the electron gun after vacuumizing to perform electron beam centering and calibration, and then performing preheating and melting printing.

Technical Field

The invention relates to a process method, in particular to a process method for improving the surface quality of an electron beam additive manufacturing part, and belongs to the technical field of additive manufacturing processes.

Background

The additive manufacturing technology is a new manufacturing means, prepares parts by a mode of accumulating materials from bottom to top, has the characteristics of high forming efficiency, wide application field and capability of preparing parts with complex structures, and can meet the personalized design and requirements of people.

Electron beam additive manufacturing is a technology in the field of metal additive manufacturing, and the general forming process of the electron beam additive manufacturing can be divided into four stages of powder laying, preheating, melting and cooling. The powder spreading stage is to uniformly spread metal powder with the thickness of 50-200 mu m on the substrate by using a powder taking doctor blade; the preheating stage is to heat the laid powder according to the three-dimensional slice information of the printed part so as to ensure the energy required in the forming process; the melting refers to a process of sintering metal powder in a selected area by using an electron beam with high energy density under a set process condition to prepare an entity; cooling refers to a process of temperature reduction in a vacuum state in the presence of a small amount of helium gas after completion of melting. At present, titanium alloy, nickel-based alloy, metal tantalum, titanium-aluminum alloy and cobalt-chromium alloy parts are mainly formed by adopting an electron beam additive manufacturing technology, the forming process of the titanium alloy is mature at the present stage, the mechanical property and the size precision of a printed part of the titanium alloy reach the standard, and the problems of rough outer surface, cracks and the like of the printed part still exist.

The research finds that the outer surface of the part manufactured by electron beam additive manufacturing is rough, which is mainly greatly related to the factors such as the thickness of the powder layer, the particle size of the powder, the diameter of beam spots and the like, and the regulation and control range of partial parameters is limited by the inherent characteristics of equipment.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the process method for improving the surface quality of the electron beam additive manufacturing part is relatively low in cost and does not need to be processed again.

The technical scheme adopted for solving the technical problems is as follows: a process method for improving the surface quality of parts manufactured by electron beam additive manufacturing comprises the steps of carrying out electron beam melting on added auxiliary materials in the melting process of the additive manufacturing, then carrying out precise remelting on the outer contour formed by the electron beam melting, then carrying out cooling process of the additive manufacturing to obtain the surface quality of the parts meeting the requirements,

wherein the roughness of the surface of the precisely remelted additive manufactured part does not exceed Ra 12.

Further, the precision remelting is performed by a laser emitted from a laser installed near a camera in a forming chamber of a powder bed type electron beam apparatus.

In a preferred mode of the above aspect, the additive manufacturing further includes a powder laying step and a preheating step, parameters of the respective steps are controlled as follows,

the thickness of the powder spreading layer in the powder spreading process is not more than 50 mu m, the preheating temperature in the preheating process is 730 ℃, the scanning speed in the melting printing process is 12000mm/s, the beam current is 5-30mA, and the laser power in the laser remelting process is 250W, the spot diameter is 100 mu m and the scanning speed is 1100 mm/s.

Further, the grain diameter of the alloy powder laid in the powder laying step is 45 to 105 μm.

The preferable mode of the proposal is that before preheating and printing, vacuumization is firstly needed after powder spreading is finished, and the specific requirements are that,

the vacuum degree of the forming chamber should reach 2X 10-3mbar, and the vacuum degree of the electron gun should reach 7X 10-5 mbar.

Furthermore, before vacuumizing, marking the center of the base plate on which the alloy powder is laid and leveling the base plate, then vacuumizing the forming bin and the electron gun, starting high voltage for electron beam centering and calibration of the electron gun after vacuumizing, and then entering preheating and melting printing procedures.

The invention has the beneficial effects that: the process method provided by the application takes laser as an energy source, the outer contour formed after electron beam melting is subjected to accurate remelting through the laser again, and finally the outer contour enters a cooling process to obtain an accurate remelting surface with the roughness not exceeding Ra12, so that the purpose of improving the surface quality of the printing part of the powder bed type electron beam equipment is achieved. The process method does not need to increase the workload of polishing, rough polishing and fine polishing independently, only needs to adapt to the addition of an accurate remelting process after the additive melting process is completed, almost does not increase the construction cost, only carries out limited improvement treatment on the existing equipment, and provides an effective solution for reducing the surface roughness of a printed piece.

Drawings

Fig. 1 is a simplified schematic diagram of a laser installation position involved in the process method for improving the surface quality of an electron beam additive manufacturing part according to the invention.

Detailed Description

In order to solve the technical problems in the prior art, the invention provides the process method for improving the surface quality of the electron beam additive manufacturing part, which has relatively low cost and does not need to be processed again. A process method for improving the surface quality of electron beam additive manufacturing parts is characterized in that: the process method comprises the steps of carrying out precise remelting on the outer contour formed after electron beam melting is carried out on the added auxiliary materials in the melting process of additive manufacturing through laser again, then entering the cooling process of additive manufacturing to obtain the surface quality of parts meeting the requirements,

wherein the roughness of the surface of the precisely remelted additive manufactured part does not exceed Ra 12. The process method provided by the application takes laser as an energy source, the outer contour formed after electron beam melting is subjected to accurate remelting through the laser again, and finally the outer contour enters a cooling process to obtain an accurate remelting surface with the roughness not exceeding Ra12, so that the purpose of improving the surface quality of the printing part of the powder bed type electron beam equipment is achieved. The process method does not need to increase the workload of polishing, rough polishing and fine polishing independently, only needs to be adapted to increase an accurate remelting process after the additive melting process is completed, the construction cost is hardly increased, only limited improvement treatment is carried out on the existing equipment, an effective solution is provided for reducing the surface roughness of a printed piece, and the installation position of a laser in the remelting equipment is shown in figure 1.

In the above embodiment, in order to obtain the best surface roughness quality, the precise remelting of the present application is performed by a laser emitted from a laser installed beside a camera of a forming chamber of a powder bed type electron beam apparatus. Correspondingly, the additive manufacturing also comprises a powder laying process and a preheating process, the parameters of each process are controlled according to the following requirements,

the thickness of the powder spreading layer in the powder spreading process is not more than 50 mu m, the preheating temperature in the preheating process is 730 ℃, the scanning speed in the melting printing process is 12000mm/s, the beam current is 5-30mA, and the laser power in the laser remelting process is 250W, the spot diameter is 100 mu m, and the scanning speed is 1100 mm/s. The grain diameter of the alloy powder laid in the powder laying process is 45-105 μm. Before preheating and printing, the powder spreading needs to be vacuumized, and the specific requirements are that the vacuum degree of a forming bin should reach 2 x 10 < -3 > mbar and the vacuum degree of an electron gun should reach 7 x 10 < -5 > mbar. Before vacuumizing, marking the center of the base plate on which the alloy powder is laid, leveling, vacuumizing the forming bin and the electron gun, starting the electron gun after vacuumizing to perform electron beam centering and calibration, and then performing preheating and melting printing.

In conclusion, the process method provided by the application also has the following advantages,

1. the invention discloses a method for improving the surface quality of electron beam additive manufacturing parts, which aims to reduce the surface roughness of a printed part by additionally arranging a laser beside a camera of a forming bin of powder bed type electron beam equipment. The laser is used as an energy source to remelt the profile of the part sintered by the electron beam, so that the forming precision can be effectively improved, the roughness of the part is reduced, the post-treatment process is greatly shortened, and a wide market is provided for the application of the additive manufacturing technology.

2. The forming precision and the surface quality of a printed product can be rapidly improved, the machining process is effectively shortened, and the method can be widely applied to the fields of aviation, aerospace and the like. The application and popularization of the method can greatly reduce the manufacturing cost, so that the development of an additive manufacturing technology is promoted, and the method has good market prospect.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The invention aims to provide a method for reducing the surface quality of an electron beam additive manufacturing part, which is used for reducing the surface quality of the electron beam additive manufacturing part (about Ra12 is reduced from Ra25-Ra 35), thereby reducing the post-treatment difficulty of a printed product and shortening the manufacturing period.

In order to achieve the purpose, the laser is added beside a camera of a forming cavity of powder bed type electron beam equipment, and the melted outer contour of the electron beam is remelted by the laser in the printing process of the powder bed type electron beam equipment so as to achieve the purpose of polishing, so that the surface quality of a printed part is reduced, and the surface forming quality is improved.

The technical scheme adopted by the invention is as follows:

the preparation stage of powder bed type electron beam forming includes setting proper amount of Ti6Al4V alloy powder with grain size distribution of 45-105 micron inside the powder supplying bin, marking and leveling substrate of 210X 210mm size, vacuumizing the forming bin and the electron gun, starting electron beam centering and calibration after the vacuum degree of the forming bin reaches 2X 10-3mbar and the vacuum degree of the electron gun reaches 7X 10-5mbar, and final preheating and printing. The main processing parameters for printing were: the thickness of the powder layer is 50 mu m, the preheating temperature is 730 ℃, the scanning speed is 800-; the laser power is 170-.

The technical scheme of the invention is based on an electron beam additive manufacturing technology, improves the existing equipment according to the characteristics and forming influence factors of the technology, and provides an effective solution for reducing the surface quality of a printed product.

Example one

The method comprises the following steps:

(1) taking 40Kg of TC4 alloy powder with the particle size distribution of 45-105 μm, and putting the powder into a powder bin of a powder bed type electron beam device;

(2) selecting a stainless steel substrate with the size of 210 multiplied by 210mm, marking the center, and placing the stainless steel substrate on a forming platform for leveling;

(3) vacuumizing the forming bin and the electron gun, starting high pressure to perform electron beam centering and calibration when the vacuum degree of the forming bin reaches 2 x 10 < -3 > mbar and the vacuum degree of the electron gun reaches 7 x 10 < -5 > mbar;

(4) importing the STL file of the print model into powder bed type electron beam equipment, repairing the model by using Magics software, adding support and slicing;

(5) selecting a Ti6Al4V material corresponding to the equipment process, and editing forming process parameters, wherein the specific parameters are as follows: the thickness of the powder layer is 60 mu m, the preheating temperature is 730 ℃ plus 750 ℃, the scanning speed is 800 plus 12000mm/s, and the beam current is 5-30 mA; the laser power is 130-.

(6) And starting preheating, starting printing, taking out the printed titanium alloy piece after printing is finished, and testing the surface roughness of the titanium alloy piece.

The printing metal powder in the step (1) is Ti6Al4V alloy, and the particle size distribution of the printing metal powder is as follows: 45-105 μm.

The printing substrate in the step (2) has the size of 210 multiplied by 210mm and is made of stainless steel.

And (4) in the early stage of the printing and forming in the step (3), the forming bin and the electron gun need to be vacuumized, and the purpose is to prevent the oxidation of metal powder and printed parts on the premise of ensuring that the forming environment is a vacuum condition.

And (5) editing the process of printing the Ti6Al4V, and adjusting the processing process parameters to obtain a printing component with high density and good surface quality. The main processing parameters comprise: the thickness of the powder layer is 60 mu m, the preheating temperature is 730 ℃ plus 750 ℃, the scanning speed is 800 plus 12000mm/s, and the beam current is 5-30 mA; the laser power is 130-.