Manufacturing method and equipment for titanium alloy part

Abstract

The invention relates to the technical field of titanium alloy preparation, in particular to a method and equipment for manufacturing a titanium alloy part. A manufacturing method of a titanium alloy part adopts a powder laying and laser heating process to print and manufacture the titanium alloy part, and comprises the following steps: firstly laying a layer of titanium alloy powder on a substrate, melting the laid powder through laser according to a set path, and solidifying the molten powder to form a titanium alloy sample. And the required titanium alloy part is printed and manufactured by circulating the powder spreading and laser heating processes for multiple times. In the manufacturing process, when a specified number of layers are printed, a titanium alloy sample needs to be heated, pressurized and flattened. The surface of the titanium alloy sample is heated, so that some unmelted particles in the titanium alloy sample can be melted, and the surface of the titanium alloy sample is flattened in a pressurizing and flattening manner, so that part of air holes can be filled with the melted particles, and the quality of the manufactured titanium alloy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy preparation, and in particular to a method and equipment for manufacturing a titanium alloy part. Background Art

[0002] Titanium alloy refers to a variety of alloy metals made of titanium and other metals. Titanium is an important structural metal developed in the 1950s. Titanium alloys are widely used in the aerospace field due to their high strength and low mass, including aircraft landing gear, fuselage skin, heat shield, compressor disc, blades, compressor casing, etc. In the prior art, titanium alloys can generally be manufactured by SLM technology.

[0003] Among them, SLM, or Selective laser melting, is a major technical approach in additive manufacturing of metal materials. This technology uses laser as the energy source, and scans the metal powder bed layer by layer according to the path planned in the three-dimensional CAD slice model. The scanned metal powder is melted and solidified to achieve the effect of metallurgical bonding, and finally the metal parts designed by the model are obtained. However, although the existing SLM technology can produce complex geometric shapes, the surface roughness of the parts produced is relatively high and it is prone to defects such as internal pores and cracks, resulting in poor quality of the produced parts. Summary of the invention

[0004] In order to solve the technical problems in the prior art that parts prepared by SLM technology have high surface roughness and are prone to internal pores, the present invention provides a method and equipment for manufacturing titanium alloy parts.

[0005] The present invention is implemented by the following technical scheme: a method for manufacturing a titanium alloy part, which uses a powder laying and laser heating process to print and manufacture the titanium alloy part, and includes the following steps: firstly, a layer of titanium alloy powder is laid on a substrate, and then the laid powder is melted by a laser according to a set path, and the melted powder is solidified to form a titanium alloy sample. The powder laying and laser heating process are repeated for multiple times to print and manufacture the required titanium alloy part.

[0006] During the entire manufacturing process, the surface roughness of the titanium alloy sample needs to be optimized when printing to a specified number of layers. The specific optimization steps are as follows:

[0007] (1) Measure the surface roughness Ra of titanium alloy samples:

[0008] (2) If Ra is less than 1 μm, continue with the powder printing operation;

[0009] (3) If Ra ≥ 1 μm, the surface of the titanium alloy sample needs to be heated at least once by laser heating; and after each heating, the surface of the titanium alloy sample needs to be flattened n times; and the surface roughness Ra of the titanium alloy sample after flattening is measured:

[0010] (4) If the surface roughness Ra of the titanium alloy sample after flattening is ≥1 μm, step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after flattening is <1 μm, then the flattening is stopped and the powder printing operation is continued.

[0011] As a further improvement of the present invention, in performing n times of flattening treatment on the surface of the titanium alloy sample, it includes the following steps:

[0012] (4.1) If the surface roughness of the titanium alloy sample after heating treatment is 1.3μm≥Ra≥1μm, the roller flattening method is selected to perform flattening treatment n times; and the surface roughness Ra of the titanium alloy sample after flattening n times is determined as follows:

[0013] (4.1.1) If 1.3 μm ≥ Ra ≥ 1 μm, then the step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after flattening treatment is less than 1 μm, then the flattening is stopped and the powder printing operation is continued;

[0014] (4.1.2) If the surface roughness Ra of the titanium alloy sample after flattening is less than 1 μm, stop flattening and continue the powder printing operation;

[0015] (4.2) If the surface roughness Ra of the titanium alloy sample after the heating treatment is greater than 1.3 μm, a pressing plate is used for flattening once, and the surface roughness of the titanium alloy sample after flattening is measured. In the n-times flattening treatment:

[0016] (4.2.1) If the surface roughness Ra of the titanium alloy sample after the mth flattening (m<n) is greater than 1.3 μm, the nth flattening operation is performed by using a pressing plate, and the surface roughness Ra of the titanium alloy sample after the nth flattening treatment is determined as follows:

[0017] (4.2.1.1) If the surface roughness Ra of the titanium alloy sample after the nth flattening is ≥ 1 μm, step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after the flattening treatment is < 1 μm, then the flattening is stopped and the powder printing operation is continued;

[0018] (4.2.1.2) If the surface roughness Ra of the titanium alloy sample after the nth flattening is less than 1 μm, stop flattening and continue the powder printing operation;

[0019] (4.2.2) If the surface roughness of the titanium alloy sample after the mth (m<n) flattening is 1.3μm≥Ra≥1μm, the roller flattening method is selected to perform nm times of flattening treatment, and the surface roughness Ra of the titanium alloy sample after the nth flattening treatment is determined as follows:

[0020] (4.2.2.1) If the surface roughness Ra of the titanium alloy sample after the nth flattening is ≥ 1 μm, the step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after the flattening treatment is < 1 μm, then the flattening is stopped and the powder printing operation is continued;

[0021] (4.2.2.2) If the surface roughness Ra of the titanium alloy sample after the nth flattening is less than 1 μm, stop the flattening and continue the powder printing operation.

[0022] As a further improvement of the present invention, before heating the titanium alloy sample, it is necessary to determine the optimal parameter combination of the titanium alloy sample during the laser heating process. The steps for determining the optimal parameter combination are as follows:

[0023] Determine the parameters that affect the laser heating process, which are laser power, scanning speed, and printing layer thickness;

[0024] The laser power range, scanning speed range and printing layer thickness range of the titanium alloy samples under printing were obtained, and the optimal parameter combination among the three parameters of laser power, scanning speed and printing layer thickness during the laser heating process was obtained through the orthogonal experimental method.

[0025] As a further improvement of the present invention, the number of laser heating times ranges from 1 to 8 times.

[0026] As a further improvement of the present invention, the number of flattening operations ranges from 2 to 9 times.

[0027] As a further improvement of the present invention, during printing, the number of layers of the titanium alloy to be prepared is divided into a layer and b layer, a:b=2:1~4:3; and the specified number of layers before printing the a layer is less than the specified number of layers after printing the b layer.

[0028] As a further improvement of the present invention, during the printing process, the particle size of the powder is 15 μm-45 μm, the laser power is 100-400 W, the laser spot diameter is 50 μm-100 μm, and the scanning speed is 500-3000 mm / s.

[0029] As a further improvement of the present invention, the substrate is preheated before printing, and the preheating temperature is 180°C-220°C.

[0030] As a further improvement of the present invention, argon gas needs to be introduced for gas protection during printing, and the flow rate of the introduced argon gas is 5L / min-20L / min.

[0031] A titanium alloy part manufacturing device, which uses the titanium alloy part manufacturing method to prepare the titanium alloy part, comprising:

[0032] A frame, on which a powder bin and a molding bin are independent of each other, both of which can move along the vertical direction of the frame, and a substrate for printing is installed in the molding bin;

[0033] A powder scraping assembly is installed on the side of the frame close to the powder bin. The powder scraping assembly moves from the powder bin to the molding bin to spread the powder in the powder bin onto the base plate of the molding bin.

[0034] The flattening assembly includes a roller flattening assembly and a pressure plate flattening assembly. The pressure plate flattening assembly is installed on the frame and is located directly above the substrate. The pressure plate flattening assembly is used to vertically pressurize the titanium alloy sample on the substrate from top to bottom; the roller flattening assembly is installed on the powder scraping assembly. The roller flattening assembly is used to roll and pressurize the titanium alloy sample on the substrate.

[0035] A laser source is located above the molding chamber and is used to heat the powder spread on the substrate;

[0036] The control system is used to control the movement of the powder scraping component, the flattening component and the laser source respectively.

[0037] As a further improvement of the present invention, the powder scraping assembly includes a driving member and a scraper. The scraper is slidably mounted on the frame, and the driving member drives the scraper to reciprocate between the powder bin and the molding bin.

[0038] As a further improvement of the present invention, the scraper is a soft scraper, and an angle is provided between the length side of the scraper and the length side of the sample, and the range of the angle is 5° to 45°.

[0039] As a further improvement of the present invention, the roller flattening assembly includes a second driving member and a roller, wherein the second driving member is connected to the roller and is used to adjust the height of the roller.

[0040] As a further improvement of the present invention, a driving member three is provided under the powder bin, and a driving member four is provided under the molding bin. The driving member three drives the powder bin to move along the vertical direction of the frame to adjust the thickness of the powder layer entering the molding bin; the driving member four drives the molding bin to move along the vertical direction of the frame to adjust the height of the substrate.

[0041] As a further improvement of the present invention, a plurality of titanium alloy samples can be printed on the substrate at one time, the plurality of titanium alloy samples are staggered, and the minimum distance between two adjacent titanium alloy samples is greater than or equal to 2 cm.

[0042] As a further improvement of the present invention, the distance between the highest point of the substrate and the lowest point of the substrate in the vertical direction of the frame does not exceed 100 μm.

[0043] The technical solution provided by the present invention has the following beneficial effects:

[0044] (1) The manufacturing method of titanium alloy parts provided by the present invention can first heat the surface of the titanium alloy sample by laser heating when it is found that the surface roughness of the titanium alloy sample is not good during the manufacturing process, so that some unmelted particles inside the titanium alloy sample can be melted, and then the surface of the titanium alloy sample can be flattened by pressurization, so that these molten particles can fill a part of the pores, thereby improving the quality of the manufactured titanium alloy.

[0045] (2) The manufacturing method of the titanium alloy part provided by the present invention, when the specified number of layers are printed by laser heating during the manufacturing process, the surface of the titanium alloy sample is stopped from being further powdered and printed, and the surface of the titanium alloy sample is heated by laser heating along the same path. The purpose of heating is to form a steady-state temperature gradient inside the titanium alloy sample during the printing process, thereby affecting the non-uniform distribution of residual stress and reducing the occurrence of interlayer cracking. At the same time, stopping printing and heating the surface of the titanium alloy sample when the specified number of layers are printed can inhibit the formation and expansion of cracks, increase the heat circulation in the titanium alloy sample, reduce the formation of unfused holes, and improve the molding quality. In addition, heating can also homogenize the microstructure distribution in the titanium alloy sample, reduce component segregation, and thus improve the mechanical properties of the prepared titanium alloy part. And immediately after heating, the surface of the heated titanium alloy sample is pressurized and flattened. Pressurization and flattening can reduce the surface roughness of the titanium alloy sample, making its surface smoother, so that the subsequent powder can be laid more evenly on the surface of the titanium alloy sample. Furthermore, by pressurizing and flattening the surface of the heated titanium alloy sample, the bonding between the layers of the titanium alloy sample during printing can be improved, thereby improving the quality of the prepared titanium alloy parts.

[0046] (3) In the manufacturing method of titanium alloy parts provided by the present invention, during the pressurizing and flattening process, the appropriate pressurizing and flattening method can be selected according to the surface roughness of the manufactured titanium alloy sample, so that the prepared titanium alloy sample can improve its quality while not being damaged by excessive pressurizing pressure during the pressurizing and flattening process, or increasing the processing time and reducing the production efficiency due to insufficient pressurizing pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A flowchart of the steps of a method for manufacturing a titanium alloy part provided by the present invention.

[0048] Figure 2 This is a schematic structural diagram of the equipment for manufacturing titanium alloy parts provided by the present invention.

[0049] Figure 3 This is an enlarged structural schematic diagram of the device for manufacturing titanium alloy parts provided by the present invention when the roller is installed on the scraper.

[0050] Figure 4 This is a schematic diagram of a plurality of titanium alloy samples on a substrate provided by the present invention being staggered along the powder spreading direction.

[0051] Figure 5 This is a schematic diagram of a situation in which a certain angle is set between the titanium alloy sample on the substrate provided by the present invention and the long side direction of the scraper.

[0052] Figure 6 The figure is a comparison diagram of the appearance of a titanium alloy part 1 manufactured by the titanium alloy part manufacturing method provided by the present invention and a titanium alloy part 2 manufactured by the titanium alloy manufacturing method provided by the present invention but without performing heating and pressurizing flattening operations on the specified number of layers during manufacturing.

[0053] Figure 7 The following are pictures of the titanium alloy part manufactured in Example 1 of the present invention and the titanium alloy part manufactured in the comparative example observed under an optical microscope.

[0054] Figure 8 The figure is a comparison chart of the tensile strength test results of the titanium alloy part manufactured in Example 1 of the present invention and the titanium alloy part manufactured in the comparative example.

[0055] The markings in the figure are: 1, frame; 11, powder bin; 12, molding bin; 121, substrate; 13, driving component three; 14, driving component four; 2, scraper; 3, roller; 4, laser; 5, galvanometer. DETAILED DESCRIPTION

[0056] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0057] In the description of the present invention, it should be noted that for directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions and positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present invention. The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. The terms "including" and "having" in the specification and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0058] SLM: Selective Laser Melting, which is a major technical approach in the additive manufacturing of metal materials. This technology uses laser as the energy source, and scans the metal powder bed layer by layer according to the path planned in the three-dimensional CAD slice model. The scanned metal powder is melted and solidified to achieve the effect of metallurgical bonding, and finally the metal parts involved in the model are obtained. When using SLM technology to prepare metal parts, it is a layer-by-layer manufacturing process. During manufacturing, each layer requires laser scanning of molten powder, and a layer of metal film is printed by laying a layer of powder and laser scanning of molten powder. In this way, the metal parts we need are prepared layer by layer.

[0059] When the applicant used the SLM technology to manufacture titanium alloy parts, it was found that as the powder printing was carried out layer by layer, the surface of the printed titanium alloy was relatively rough. If the powder printing was continued on the rough surface, the quality of the manufactured titanium alloy parts would be relatively poor, and defects such as pores, cracks, and lack of fusion would be prone to occur, resulting in the quality of the manufactured titanium alloy parts not meeting the requirements.

[0060] In the present application, when the applicant manufactures titanium alloy parts through SLM technology, the surface of the manufactured titanium alloy sample is heated by laser scanning every specified number of layers, and the surface of the titanium alloy sample is flattened by applying pressure after heating, thereby improving the quality of the prepared titanium alloy parts.

[0061] The following is a description of the method for manufacturing a titanium alloy part in the present application:

[0062] First of all, before manufacturing titanium alloy parts, it is necessary to set the process parameters in the titanium alloy manufacturing process. The specific process parameter settings are as follows:

[0063] (1) Titanium alloy powder

[0064] When selecting titanium alloy powder, spherical powder with a particle size of 15-53μm and low impurity content is preferred. Powders within this range have good fluidity and high stability, and can be well melted and formed by laser. And when selecting, you should try to choose powders with high sphericity. Spherical powders have better fluidity and stacking properties, which can make the laser energy absorption more uniform, thereby improving the forming quality of titanium alloys. Since titanium alloys are generally used in the field of aerospace materials, the quality requirements for the manufactured products are relatively high. Therefore, when screening titanium alloy powders, the purity requirements are generally relatively high to ensure the performance and forming quality of the prepared TC4 alloy.

[0065] (II) Laser parameters

[0066] Regarding laser power: In this embodiment, the laser power can be selected between 100W and 400W. The purpose of selecting this range is that if the laser power is too low, the titanium alloy powder laid on the substrate 121 will not be completely melted, and the prepared titanium alloy will have defects such as pores and unfused parts. If the laser power is too high, the molten pool temperature may be too high, resulting in oxidation, nitridation, spheroidization, and large thermal stress, thereby causing cracks and other problems.

[0067] Regarding scanning speed: In this embodiment, the laser scanning speed is generally in the range of 500mm / s-3000mm / s. The purpose of selecting this range is that if the laser scanning speed is too fast, the powder will not be able to melt completely in time, so the printed sample is prone to unfused defects; and if the laser scanning speed is too slow, the molten pool will exist for too long, too much heat will accumulate, and it is easy to produce large thermal stress and deformation.

[0068] Regarding the spot diameter: In this embodiment, the spot diameter can usually be selected between 50μm and 100μm. The purpose of selecting this range is that if the spot diameter is too small, it can increase the laser energy density and facilitate the manufacture of fine structures, but it may also increase the porosity and surface roughness. Although a larger spot diameter can improve the forming efficiency of titanium alloy parts, it will reduce the forming accuracy.

[0069] Regarding the thickness of the powder layer: In this embodiment, the thickness of the powder layer can be between 20μm and 50μm. If the powder layer is too thin, the molding efficiency will be low and the manufacturing time will be increased. If the powder layer is too thick, it will be difficult for the laser energy to penetrate the entire powder layer, which may lead to insufficient melting of the powder during laser scanning, making it easy for pores and defects to appear inside the produced titanium alloy sample.

[0070] Atmosphere protection: During the entire manufacturing process, high-purity argon or nitrogen is usually used as a protective gas to prevent the titanium alloy parts from being oxidized and nitrided during the molding process. The flow rate of the gas introduced is generally between 5L / min-20L / min. The specific flow rate can be adjusted according to the specific conditions of the equipment and titanium alloy parts.

[0071] After adjusting the above parameters, the titanium alloy parts can be manufactured. The substrate 121 needs to be preheated before powder printing, and the preheating temperature can be about 200°C. The purpose of preheating is to reduce the thermal stress of the titanium alloy sample during the laser scanning melting and molding process, prevent the manufactured parts from cracking and deformation, and improve the molding quality.

[0072] Then adjust the position and height of the substrate 121 so that the substrate 121 is below the laser. After adjustment, the driving member 3 13 drives the powder bin 11 to be raised by a layer thickness, which can be set according to the thickness of each layer of the titanium alloy parts manufactured in the actual manufacturing process. Then, the powder is spread on the substrate 121 through the powder scraping assembly. After the powder is spread, start the laser source, which scans and melts the titanium alloy powder on the substrate 121 through the path set by the program. The melted powder will also solidify immediately, thereby forming a titanium alloy sample with a layer structure.

[0073] The titanium alloy sample is printed layer by layer by repeating the powder laying operation and melting and solidifying through laser scanning.

[0074] In the process of manufacturing titanium alloy samples layer by layer, when we print to the specified number of layers, we need to optimize the surface roughness of the titanium alloy samples. Figure 1 As shown, the specific optimization steps are as follows:

[0075] (1) Measure the surface roughness Ra of the titanium alloy sample, and make the following judgment on the surface roughness of the titanium alloy sample:

[0076] (2) If Ra is less than 1 μm, continue with the powder printing operation.

[0077] (3) If Ra ≥ 1 μm, the surface of the titanium alloy sample needs to be heated at least once by laser heating. After each heating, the surface of the titanium alloy sample needs to be flattened n times, and the surface roughness Ra of the flattened titanium alloy sample is measured, and the measured surface roughness Ra of the flattened titanium alloy sample is compared as follows:

[0078] (4) If the surface roughness Ra of the titanium alloy sample after flattening is ≥1 μm, step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after flattening is <1 μm, then the flattening is stopped and the powder printing operation is continued.

[0079] During the laser heating process, the scanning path of the laser heating is the same as the path of the laser during the printing process. The laser power and scanning speed during the laser heating process are both lower than the laser power and scanning speed during the powder printing process. The purpose of this limitation is to avoid the volume energy density of the titanium alloy sample being too high during the laser heating process, because the volume energy density of the titanium alloy sample being too high may cause the manufactured titanium alloy parts to overheat, have many pores and cracks inside, and thus greatly affect the quality of the manufactured titanium alloy parts.

[0080] In this embodiment, when it is found during the manufacturing process that the surface roughness of the titanium alloy sample is not good, the surface of the titanium alloy sample can be heated by laser heating first, so that some unmelted particles inside the titanium alloy sample can be melted, and then the surface of the titanium alloy sample can be flattened by pressurization, so that these molten particles can fill a part of the pores, thereby improving the quality of the manufactured titanium alloy.

[0081] Among them, for printing to a specified number of layers, the specified number of layers can be between 30 and 120 layers. In the actual manufacturing process, a series of preliminary experiments can be performed to obtain the best specified number of layers under certain specific parameter conditions. The operation of the preliminary experiment is the same as that of the present embodiment, except that the purpose of the preliminary experiment is to obtain the number of layers under a specific value for heating and flattening, so that the quality of the manufactured titanium alloy sample is the best. In this way, in the subsequent manufacturing process, only this set of optimal process parameters is used to manufacture the titanium alloy sample.

[0082] In addition, in this embodiment, two different pressurization and flattening methods are designed. One is the pressurization and flattening method of the pressure plate, and the other is the pressurization and flattening method of the roller 3. Among them, the minimum pressure generated by the pressurization and flattening method of the pressure plate is greater than the pressurization and flattening method of the roller 3. Therefore, in this embodiment, the surface roughness of the titanium alloy sample after the heat treatment is measured and judged. The specific judgment process is as follows:

[0083] In performing n-times flattening treatment on the surface of a titanium alloy sample, the following steps are included:

[0084] (4.1) If the surface roughness of the titanium alloy sample after the heat treatment is 1.3 μm ≥ Ra ≥ 1 μm, the roller 3 is used to perform n-times of flattening treatment, and the surface roughness Ra of the titanium alloy sample after the n-times of flattening is determined.

[0085] (4.2) If the surface roughness Ra of the titanium alloy sample after heat treatment is greater than 1.3 μm, a pressing plate is used to perform a flattening operation, and the surface roughness Ra of the titanium alloy sample after flattening is measured.

[0086] Among them, after completing step (4.1), it is also necessary to measure the surface roughness of the titanium alloy sample after the roller 3 is pressed and flattened n times and make the following judgment:

[0087] (4.1.1) If the surface roughness of the titanium alloy sample after n times of roller 3 pressurization and flattening treatment is 1.3μm≥Ra≥1μm, step (3) needs to be repeated until the surface roughness of the titanium alloy sample after the flattening treatment is Ra<1μm, then the pressurization and flattening operation is stopped and the powder printing operation is continued.

[0088] (4.1.2) If the surface roughness Ra of the titanium alloy sample after n times of roller 3 pressing and flattening treatment is less than 1 μm, the roller 3 pressing and flattening treatment is stopped and the powder printing operation is continued.

[0089] (4.2) If the surface roughness Ra of the titanium alloy sample after the heating treatment is greater than 1.3 μm, a pressing plate is used for flattening once, and the roughness of the titanium alloy sample after flattening is measured. In the n-times flattening treatment:

[0090] (4.2.1) If the roughness Ra of the titanium alloy sample after the mth flattening (m<n) is greater than 1.3 μm, the nth flattening operation is performed by using a pressing plate, and the surface roughness Ra of the titanium alloy sample after the nth flattening treatment is determined as follows:

[0091] (4.2.1.1) If the roughness Ra of the titanium alloy sample after the nth flattening is ≥ 1 μm, step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after the flattening treatment is less than 1 μm, then the flattening is stopped and the powder printing operation is continued;

[0092] (4.2.1.2) If the surface roughness Ra of the titanium alloy sample after the nth flattening is less than 1 μm, stop flattening and continue the powder printing operation;

[0093] (4.2.2) If the roughness of the titanium alloy sample after the m-th (m<n) flattening is 1.3μm≥Ra≥1μm, the roller 3 flattening method is selected to perform nm times of flattening treatment, and the surface roughness Ra of the titanium alloy sample after the n-th flattening treatment is determined as follows:

[0094] (4.2.2.1) If the roughness Ra of the titanium alloy sample after the nth flattening is ≥ 1 μm, the step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after the flattening treatment is less than 1 μm, then the flattening is stopped and the powder printing operation is continued;

[0095] (4.2.2.2) If the surface roughness Ra of the titanium alloy sample after the nth flattening is less than 1 μm, stop the flattening and continue the powder printing operation.

[0096] Among them, each cycle of step (3) requires making judgments of step (4.1) and step (4.2) when the surface of the titanium alloy sample is subjected to n times of pressurization and flattening treatment after heating, and making judgments of step (4.1.1) and step (4.1.2) when executing step (4.1), and making judgments of step (4.2.1) and step (4.2.2) when executing step (4.2.1). It is also necessary to make judgments of step (4.2.1.1) and step (4.2.1.2) when executing step (4.2.2), and to make judgments of step (4.2.2.1) and step (4.2.2.2) when executing step (4.2.2).

[0097] The appropriate pressurization and flattening method is selected through the above step-by-step judgment and the judgment results. The appropriate pressurization and flattening method is selected so that the quality of the prepared titanium alloy sample is improved while the titanium alloy sample will not be damaged due to excessive pressurization pressure during the pressurization and flattening process, or the processing time is increased due to too low pressurization pressure, thereby reducing production efficiency.

[0098] Before the actual treatment, the pressure of the pressing plate and the pressure of the roller 3 can be set according to the results of the test experiment. When selecting a suitable pressure range for the pressing plate to press and flatten, multiple groups of titanium alloy samples with the same surface roughness can be selected, and the surface of the titanium alloy sample can be flattened by applying different pressures when the pressing plate is pressed. The surface roughness and internal structure of the titanium alloy sample after the flattening treatment are analyzed and compared, and the optimal data is found through analysis and comparison. The pressure range of the roller 3 pressurization and flattening treatment can also be obtained through the above-described operation. In the actual operation process, the group of data with the best pressing pressure of the pressing plate and the pressing pressure of the roller 3 can be selected to pressurize and flatten the surface of the titanium alloy sample. Through this treatment, it is possible to select a suitable pressurization and flattening method to flatten the surface of the titanium alloy sample after heating, so as to achieve effective pressurization and flattening of the heated titanium alloy sample without damaging the titanium alloy sample due to excessive pressurization pressure or increasing the processing time and reducing production efficiency due to too low pressurization pressure. In addition, in the present embodiment, the surface of the titanium alloy sample is flattened by pressurizing after heating, so that the surface of the titanium alloy sample is relatively smooth, which facilitates more uniform spreading of powder in the subsequent spreading, thereby improving the quality of the printed titanium alloy sample.

[0099] In this embodiment, by selecting a suitable pressurization and flattening method according to the different surface roughness of the titanium alloy samples, the pressurization and flattening effect can be improved while reducing the number of cyclic laser heating and pressurization and flattening, thereby improving the quality of the manufactured titanium alloy samples.

[0100] It can be understood that in this embodiment, when the specified number of layers is printed by laser heating during the manufacturing process, the surface of the titanium alloy sample is stopped from being further powdered, and the surface of the titanium alloy sample is heated by laser heating along the same path. The purpose of heating is to form a steady-state temperature gradient inside the titanium alloy sample during the printing process, thereby affecting the non-uniform distribution of residual stress and reducing the occurrence of interlayer cracking. At the same time, stopping printing and heating the surface of the titanium alloy sample when the specified number of layers is printed can inhibit the formation and expansion of cracks, increase the heat circulation in the titanium alloy sample, reduce the formation of unfused holes, and improve the molding quality. In addition, heating can also homogenize the microstructure distribution in the titanium alloy sample, reduce component segregation, and thus improve the mechanical properties of the prepared titanium alloy parts. And immediately after heating, the surface of the heated titanium alloy sample is pressurized and flattened. Pressurization and flattening can reduce the surface roughness of the titanium alloy sample, making its surface smoother, so that the subsequent powder can be laid more evenly on the surface of the titanium alloy sample. In addition, by pressurizing and flattening the surface of the heated titanium alloy sample, the bonding between the layers of the titanium alloy sample during printing can be improved, thereby improving the quality of the prepared titanium alloy parts.

[0101] In the laser heating process of this embodiment, since the laser heating is mainly affected by the following three parameters: laser power, laser scanning speed and printing layer thickness. Therefore, the applicant also studied and determined the optimal parameter combination in the laser heating process. In this embodiment, the applicant determined the optimal parameter combination in the laser heating process by orthogonal test method.

[0102] Among them, the orthogonal experiment method is a scientific method for studying and processing multi-factor experiments. It uses a standardized table - orthogonal table to select experimental conditions, arrange experimental plans and conduct experiments, and find better production conditions through fewer experiments, that is, the optimal or better experimental plan.

[0103] The orthogonal array is generally expressed as: L n (m k ). Where L represents the orthogonal array, k represents the number of index factors or the number of columns in the orthogonal array. m represents the number of different levels or treatments under each factor. n represents the number of experiments or the number of rows in the orthogonal array, n = k*(m-1)+1.

[0104] In this embodiment, the orthogonal table shows that the laser power during the laser heating process is 120 W, the scanning speed is 1600 mm / s, and the printing layer thickness is 30 μm.

[0105] When the laser heats and prints the powder laid on the substrate 121, it will first obtain the optimal parameters for printing titanium alloy parts through a series of preliminary experiments. The optimal parameters are as follows: select spherical powder with a particle size of 15-53μm and low impurity content, and a powder layer thickness of 30μm; the laser spot diameter is 100μm, the laser power is 200W, and the scanning speed is 1600mm / s. When printing, high-purity argon can be selected as gas protection, the argon flow rate can be 5-20L / min, and the substrate 121 needs to be preheated to 200℃ before printing.

[0106] Since the manufacturing method of this embodiment is to lay powder layer by layer on the substrate 121, and melt the powder by laser heating, and then quickly solidify to form a layer of titanium alloy sample. The desired titanium alloy parts are prepared by laying powder layer by layer and laser scanning the molten powder. Therefore, when preparing titanium alloy parts by the manufacturing method of the embodiment, the number of layers to be printed for the titanium alloy parts to be prepared can be divided into two parts, namely a layer and b layer, and the ratio of a layer to b layer can be a:b=2:1~4:3. When printing, the first a layer is printed first, and then the b layer is printed on the basis of the a layer. And when printing the first a layer, its specified number of layers is less than the specified number of layers when printing the rear b layer. The purpose of this setting is that in the process of laser scanning powder to realize layer-by-layer printing of titanium alloy parts, as the number of printed layers increases, heat accumulation will occur in the titanium alloy sample, so the situation of excessive heat accumulation in the titanium alloy sample can be reduced by increasing the specified number of layers, because excessive heat accumulation can easily lead to excessive residual stress inside the manufactured titanium alloy parts, thereby making the manufactured products easy to crack. The designated number of layers refers to the number of layers after which the powder printing is stopped and the surface of the titanium alloy sample is laser heated and pressurized. This designated number of layers can be determined according to the total number of layers of the titanium alloy sample to be printed, and the designated number of layers is different when manufacturing titanium alloy parts of different thicknesses. In addition, when other alloy parts are manufactured by the above manufacturing method, the process parameters and designated number of layers are also different.

[0107] In addition, the applicant also provides a titanium alloy part manufacturing device, which manufactures titanium alloy parts through the above-mentioned manufacturing method.

[0108] Please refer to Figure 2 As shown, the device includes a frame 1, a powder scraping assembly, a flattening assembly, a laser source and a control system. The control system can be a PLC controller, which is used to control the start and stop of various operations in the entire device. The frame 1 is provided with a powder bin 11 and a molding bin 12 that are independent of each other. The powder bin 11 is used to provide titanium alloy powder during printing, and the molding bin 12 is used to prepare titanium alloy parts. The powder bin 11 and the molding bin 12 are arranged in parallel along the length direction of the frame 1. A substrate 121 for manufacturing titanium alloy parts is installed in the molding bin 12. Before manufacturing the titanium alloy sample, the substrate 121 needs to be leveled so that the highest point and the lowest point on the horizontal plane of the substrate 121 do not exceed 100μm. Multiple titanium alloy samples can be printed on the substrate 121 at a time, and the multiple titanium alloy samples are staggered, and the minimum distance between multiple adjacent titanium alloy samples is greater than or equal to 2cm. This arrangement can prevent the excess powder from splashing onto the surface of the titanium alloy sample when the fan on the equipment for manufacturing titanium alloy parts removes excess powder on the substrate 121 after the titanium alloy sample is formed by laser scanning titanium alloy powder, thereby affecting the quality of the produced titanium alloy part. Figure 4 As shown, Figure 4The middle left picture shows that multiple samples on the substrate 121 are not placed in a staggered manner along the powder spreading direction. Figure 4 The middle right picture shows that multiple samples on the substrate 121 are staggered along the powder spreading cabin. In this embodiment, by setting the multiple samples on the substrate 121 to be staggered with each other, and the distance between two adjacent titanium alloy samples is greater than or equal to 2 cm, the above-mentioned problems can be effectively avoided, thereby improving the quality of the prepared titanium alloy parts. In addition, the multiple samples are staggered, and when individual samples are warped or damaged, the scraper 2 is easily damaged when it passes back and forth during the powder spreading process, and it is also easy to cause subsequent titanium alloy samples to be scratched due to damage to the scraper 2. Therefore, in the actual design process, the multiple titanium alloy samples on the substrate 121 can be staggered along the powder spreading direction to avoid the above situation.

[0109] The powder scraping assembly is movably mounted on the frame 1 and is arranged on one end of the powder bin 11 away from the molding bin 12. The powder scraping assembly includes a driving member 1 and a scraper 2, wherein the driving member 1 is mounted on the frame 1, and the scraper 2 is slidably mounted on the frame 1, and the driving member 1 is connected to the scraper 2, and the driving member 1 is used to drive the scraper 2 to move back and forth between the molding bin 12 and the powder bin 11. A driving member 3 13 is provided below the powder bin 11, and the driving member 3 13 is connected to the powder bin 11, and the driving member 3 13 is used to drive the powder bin 11 to move along the vertical direction of the frame 1 to adjust the thickness of the powder layer entering the molding bin 12. A driving member 4 14 is also provided below the molding bin 12, and the driving member 4 14 is connected to the molding bin 12, and the driving member 4 14 is used to drive the molding bin 12 to move along the vertical direction of the frame 1 to adjust the height of the substrate 121. During the manufacturing process of titanium alloy parts, after each layer of titanium alloy powder is printed, the height of the substrate 121 can be adjusted by the driving member 14, so that the substrate 121 is lowered by one printing layer thickness. At this time, the upper surface of the titanium alloy sample printed on the substrate 121 is flush with the powder bin 11, and then the driving member 13 is used to drive the powder bin 11 to rise by one layer thickness, so that the powder in the powder bin 11 can be scraped to the surface of the titanium alloy sample under the action of the powder scraping assembly.

[0110] It is understandable that in this embodiment, the scraper 2 can be a soft scraper 2, which can generally be made of silicone, rubber, carbon fiber (such as a brush scraper 2) or other flexible materials. The function of the scraper 2 is to scrape the powder rising from the powder bin 11 onto the substrate 121 of the molding bin 12. The soft scraper 2 is selected because the soft scraper 2 itself has elasticity, and it will only slightly collide with the surface of the manufactured titanium alloy part when spreading the powder, and this collision will not cause damage to the manufactured titanium alloy part, thereby improving the quality of the manufactured titanium alloy part.

[0111] In addition, in this embodiment, before printing the titanium alloy part by laser scanning, Figure 5As shown, the titanium alloy sample can be adjusted on the substrate 121 so that a certain angle is set between the longest side of the titanium alloy sample to be manufactured and the long side of the scraper 2, and the angle range can be 5° to 45°. Figure 5 The left picture shows the placement of the titanium alloy sample on the substrate 121 before adjustment. Figure 5 The right picture shows the placement of the titanium alloy sample on the substrate 121 after adjustment. The purpose of setting the angle is to prevent the scraper 2 from moving back and forth on the surface of the titanium alloy sample when spreading powder. By setting a certain angle between the longest side of the titanium alloy sample to be manufactured and the long side of the scraper 2, the contact area between the scraper 2 and the titanium alloy sample can be reduced when the scraper 2 is scraping powder, thereby effectively reducing the collision of the scraper 2 and ensuring the integrity of the structural characteristics of the manufactured titanium alloy part.

[0112] The laser source is used to heat the powder laid on the substrate 121. The laser source includes a laser 4 and a galvanometer 5. The laser 4 is used to emit laser light to the galvanometer 5, and the galvanometer 5 may generally include an XY optical scanning head, an electronic drive amplifier, and an optical reflective lens. The PLC controller converts the path that the laser needs to scan into an electrical signal, and drives the optical scanning head by driving the amplifier circuit, so that the optical reflective lens controls the deflection of the laser beam in the XY plane, thereby controlling the laser beam to move along the set path on the substrate 121. In this way, the powder laid on the substrate 121 is heated by the laser beam, and the heated powder is melted and solidified to achieve a metallurgical bonding effect, thereby printing a titanium alloy sample on the substrate 121.

[0113] The flattening assembly includes a roller 3 flattening assembly and a pressure plate flattening assembly, and the pressure plate flattening assembly is installed on the frame 1 and is arranged directly above the substrate 121. The pressure plate flattening assembly is used to pressurize the surface of the titanium alloy sample on the substrate 121 from top to bottom. The roller 3 flattening assembly is installed on the powder scraping assembly, and the roller 3 flattening assembly is used to roll and pressurize the titanium alloy sample on the substrate 121. When the surface of the titanium alloy sample is pressurized, a suitable pressurization method can be selected according to the surface roughness of the titanium alloy sample. In this embodiment, if the surface roughness of the titanium alloy sample to be flattened Ra>1.3μm, the pressure plate flattening method is selected to pressurize and flatten the surface of the titanium alloy sample. If the surface roughness of the titanium alloy sample to be flattened is 1.3μm≥Ra≥1μm, the roller 3 flattening method is selected to pressurize and flatten the surface of the titanium alloy sample. If the surface roughness Ra of the titanium alloy sample is less than 1 μm, the pressurization and flattening of the surface of the titanium alloy sample is stopped, and the powder spreading and printing operation on the surface of the titanium alloy sample is continued through the powder scraping assembly.

[0114] It is understandable that during the process of applying pressure by roller 3, roller 3 needs to keep in contact with and roll with the surface of the pressed titanium alloy sample, so that roller 3 can evenly distribute the pressure on the surface of the titanium alloy sample, avoiding the situation where the local pressure on the surface of the titanium alloy sample is too large or too small, so that the surface of the processed titanium alloy part obtains more consistent physical properties and surface quality. At the same time, the pressurization method of roller 3 is relatively gentle, and the impact force on the surface of the titanium alloy sample is small, which can effectively reduce the damage to the titanium alloy sample, thereby further improving the quality of the manufactured titanium alloy parts. In addition, the device for applying pressure by roller 3 is simple in structure, easy to manufacture, install and maintain, which not only reduces the manufacturing cost of the equipment for manufacturing titanium alloy parts, but also reduces the probability of equipment failure, and improves the stability and reliability of the production of titanium alloy parts.

[0115] The pressing plate flattening assembly includes a pressing plate and a driving member 5. The pressing plate is arranged directly above the substrate 121. The driving member 5 is connected to the pressing plate. The driving member 5 controls the pressing plate to move along the vertical direction of the frame 1 to realize the operation of applying pressure and flattening the surface of the titanium alloy sample on the substrate 121 through the pressing plate. The roller 3 flattening assembly includes a driving member 2 and a roller 3. The driving member 2 and the roller 3 are both installed on the scraper 2. The driving member 2 is connected to the roller 3. Please refer to Figure 2 and Figure 3 As shown, the roller 3 is arranged on the side of the scraper 2 away from the powder bin 11. The driving member 2 is used to adjust the height of the roller 3, so that when rolling pressurization is required, the height of the roller 3 can be adjusted by the driving member 2, so that when the roller 3 flattens the titanium alloy sample on the substrate 121, the lower surface of the roller 3 abuts against the titanium alloy sample. And the roller 3 realizes rolling pressurization on the surface of the titanium alloy sample on the substrate 121 as the scraper 2 moves on the substrate 121, so that the surface of the titanium alloy sample is smoother. By pressing and flattening the surface of the titanium alloy sample after heating, the surface of the titanium alloy sample is smoother, which facilitates the subsequent powder to be evenly laid on the surface of the titanium alloy sample, thereby improving the quality of the prepared titanium alloy parts.

[0116] Among them, the applicant manufactured a titanium alloy piece by the manufacturing method of this embodiment, which is named titanium alloy piece 1. Another titanium alloy piece is manufactured, which is named titanium alloy piece 2. The manufacturing method of titanium alloy piece 2 is the same as that of this embodiment, except that the titanium alloy piece 2 will not be heated and pressed at the specified number of layers during manufacturing. The two manufactured titanium alloy pieces are put together for comparison, and the following is obtained: Figure 6 Results shown.

[0117] By observation Figure 6It can be seen that the surface of titanium alloy part 1 manufactured by the manufacturing method of this embodiment is obviously smoother than the surface of titanium alloy part 2 manufactured. This shows that when titanium alloy parts are manufactured by the manufacturing method of this embodiment, heating and pressurization are performed when printing to a specified number of layers by laser scanning heating, so that the surface of the manufactured titanium alloy parts is smoother, which can effectively improve the forming quality of the manufactured titanium alloy parts.

[0118] Example 1

[0119] The following describes the manufacturing process of a titanium alloy part of a specific size. The length, width and height of the titanium alloy part are all 30 mm, and a total of 1000 layers need to be printed by laser scanning. When the titanium alloy part is printed by laser scanning, the number of printed layers is determined by the print layer thickness of the obtained titanium alloy sample and the height of the titanium alloy sample to be prepared. Before printing, the 1000 layers are divided into two parts, the first 600 layers and the last 400 layers. The specific manufacturing process is as follows: (1) Adjust the various parameters of the equipment for manufacturing titanium alloy parts. (2) The powder bin 11 is pushed up by the driving member 3 13 by a layer thickness of 30 μm. The scraper 2 moves from the right side of the powder bin 11 to the left side of the molding bin 12. At this time, the scraper 2 pushes the powder in the powder bin 11 onto the substrate 121 on the molding bin 12. During this process, it can be observed with the naked eye. If the powder on the substrate 121 is not evenly spread, the scraper 2 can be driven by the driving member 1 to move back and forth on the substrate 121 to achieve the leveling operation. (3) After the powder is laid flat, the laser 4 and the galvanometer 5 can be started. The laser generated by the laser 4 to the galvanometer 5 heats the powder laid on the substrate 121 according to the path set by the program, so that the titanium alloy powder laid on the substrate 121 can be melted and solidified into a titanium alloy sample, thereby printing a layer of titanium alloy sample on the substrate 121. (4) After printing a layer of titanium alloy sample, the forming chamber 12 can be driven downward by the driving member 14 by a layer thickness of 30μm. Then move the scraper 2 from the leftmost end of the frame 1 to the rightmost end of the frame 1, that is, the right end of the powder chamber 11. (5) Steps (2), (3) and (4) are cycled in sequence until 50 layers of titanium alloy samples are printed. At this time, the scraper 2 is no longer scraping powder, and the laser power is adjusted to 120W and the scanning speed is adjusted to 1300mm / s. (6) The surface of the titanium alloy sample with a 50-layer structure is heated by the laser generated by the laser 4 on the galvanometer 5. At this time, the scanning path of the laser is the same as the path of step (3). After laser heating, the surface of the heated titanium alloy sample can be pressurized by the flattening component, and the number of pressurizations can be 5 times. (7) After repeating step (6) five times, the surface roughness of the titanium alloy sample is less than 1μm, and the powder spreading operation can be continued. (8) The first 600 layers of the titanium alloy sample are printed by repeating steps (2), (3) and (4) in sequence. And steps (6) and (7) need to be repeated at the 100th layer, 150th layer, 200th layer, 250th layer, 300th layer, 350th layer, 400th layer, 450th layer, 500th layer, 550th layer and 600th layer. (9) After heating and flattening the titanium alloy sample having 600 layers, the next 400 layers are printed on the basis of the titanium alloy sample having 600 layers by repeating steps (2), (3) and (4).And after printing 400 layers, when printing to the 700th layer, the 800th layer, the 900th layer and the 1000th layer, the scraper 2 is no longer performing the powder scraping operation, and the laser power is adjusted to 120W, the scanning speed is adjusted to 1300mm / s, and the laser generated by the laser 4 on the galvanometer 5 is used to heat the surface of the titanium alloy sample with a specified number of layers. At this time, the scanning path of the laser is the same as the path of step (3). After the laser heating, the surface of the heated titanium alloy sample can be pressurized by a flattening component, and the number of pressurizations can be 5 times. (7) After repeating step (6) twice, the surface roughness of the titanium alloy sample is less than 1μm, and a titanium alloy part with a 1000-layer structure is obtained.

[0120] Comparative Example

[0121] The comparative example also describes the manufacturing process of a titanium alloy part of a specific size. The length, width and height of the titanium alloy part are all 30 mm, and a total of 1000 layers need to be printed by laser scanning. The specific manufacturing process is as follows: (1) Adjust the various parameters of the equipment for manufacturing titanium alloy parts, which are the same as the parameters of the embodiment. (2) The powder bin 11 is pushed up by the driving member 3 13 by a layer thickness of 30 μm. The scraper 2 moves from the right side of the powder bin 11 to the left side of the molding bin 12. At this time, the scraper 2 pushes the powder in the powder bin 11 onto the substrate 121 on the molding bin 12. During this process, it can be observed with the naked eye. If the powder on the substrate 121 is not evenly laid, the scraper 2 can be driven by the driving member 1 to move back and forth on the substrate 121 to achieve the leveling operation. (3) After the powder is laid flat, the laser 4 and the galvanometer 5 can be started. The laser emitted by the laser 4 to the galvanometer 5 heats the powder laid on the substrate 121 according to the path set by the program, so that the titanium alloy powder laid on the substrate 121 can be melted and solidified into a titanium alloy sample, thereby printing a layer of titanium alloy sample on the substrate 121. (4) After printing a layer of titanium alloy sample, the forming bin 12 can be driven downward by the driving part 14 by a layer thickness of 30μm. Then move the scraper 2 from the leftmost end of the frame 1 to the rightmost end of the frame 1, that is, the right end of the powder bin 11. (5) Steps (2), (3) and (4) are repeated in sequence until a titanium alloy part with a 1000-layer structure is printed.

[0122] Performance Testing

[0123] (A) Observe the internal microstructure of the manufactured titanium alloy parts through an optical microscope

[0124] The titanium alloy parts manufactured by the manufacturing method of Example 1 and the titanium alloy parts manufactured by the manufacturing method of the comparative example were observed under an optical microscope respectively, and the following results were obtained: Figure 7 Results shown.

[0125] By observation Figure 7 It can be seen that the surface of the titanium alloy part manufactured by the manufacturing method of Example 1 has no holes, while the surface of the titanium alloy part manufactured by the manufacturing method of the comparative example has many holes. This shows that in the manufacturing method of Example 1, heating and flattening the surface of the titanium alloy part sample at a specified number of layers can help form a stable temperature gradient in the titanium alloy sample, so that the residual stress in the titanium alloy sample is evenly distributed and the interlayer cracking during the manufacturing process is reduced. At the same time, heating can make some unmelted particles inside the titanium alloy sample melt and solidify, thereby reducing the formation of holes in the titanium alloy sample and improving the quality of the manufactured titanium alloy parts.

[0126] (II) Tensile strength test

[0127] The specific operation is as follows: At room temperature, a quasi-static tensile test was performed on a YSH-229WJ-10T computer-controlled electronic universal material testing machine (Jinan Wansi Electrical Equipment Co., Ltd., Jinan, China). The test standard is based on ASTM E8 "Methods for tensile testing of metallic materials". First, the titanium alloy parts were preloaded with a failure load not exceeding 30% of the expected failure load, and the tensile test was performed after ensuring that there were no abnormalities. During stretching, a quasi-static tensile load was applied to the titanium alloy parts at a stretching rate of 2 mm / min until the titanium alloy parts were damaged or the load was reduced by 40% from the maximum value. Then the loading was stopped, and the maximum load and failure mode were recorded. Each set of tensile tests was performed three times, and the average value was taken as the final data.

[0128] Through the above operations, the tensile strength of the titanium alloy parts manufactured in Example 1 and the titanium alloy parts manufactured in the comparative example were tested and the results were as follows: Figure 8 result.

[0129] pass Figure 8 It can be seen that the tensile strength of the titanium alloy part manufactured by the manufacturing method of Example 1 is much greater than the tensile strength of the titanium alloy part manufactured by the manufacturing method of the comparative example. The difference between the manufacturing method of Example 1 and the manufacturing method of the comparative example is that when manufacturing the titanium alloy part, Example 1 heats and presses the titanium alloy part when printing to a specified number of layers, which shows that the tensile strength of the manufactured titanium alloy part can be improved by heating and pressurizing, thereby improving the mechanical properties of the manufactured titanium alloy part.

[0130] The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for manufacturing a titanium alloy part, characterized in that: The process of powder laying and laser heating is used to print and manufacture titanium alloy parts, which includes the following steps: firstly, a layer of titanium alloy powder is laid on a substrate, and then the laid powder is melted by laser according to a set path, and the melted powder is solidified to form a titanium alloy sample; the powder laying and laser heating process are repeated for many times to print and manufacture the required titanium alloy parts; During the entire manufacturing process, the surface roughness of the titanium alloy sample needs to be optimized when printing to a specified number of layers. The specific optimization steps are as follows: (1) Measure the surface roughness Ra of titanium alloy samples: (2) If Ra is less than 1 μm, continue with the powder printing operation; (3) If Ra ≥ 1 μm, the surface of the titanium alloy sample needs to be heated at least once by laser heating; and after each heating, the surface of the titanium alloy sample needs to be flattened n times; and the surface roughness Ra of the titanium alloy sample after flattening is measured: (4) If the surface roughness Ra of the titanium alloy sample after flattening is ≥1 μm, step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after flattening is <1 μm, then the flattening is stopped and the powder printing operation is continued.

2. The method for manufacturing a titanium alloy part according to claim 1, characterized in that: It includes the following steps: In performing n-times flattening treatment on the surface of a titanium alloy sample, the following steps are included: (4.1) If the surface roughness of the titanium alloy sample after heating treatment is 1.3μm≥Ra≥1μm, the roller flattening method is selected to perform flattening treatment n times; and the surface roughness Ra of the titanium alloy sample after flattening n times is determined as follows: (4.1.1) If 1.3 μm ≥ Ra ≥ 1 μm, then the step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after flattening treatment is less than 1 μm, then the flattening is stopped and the powder printing operation is continued; (4.1.2) If the surface roughness Ra of the titanium alloy sample after flattening is less than 1 μm, stop flattening and continue the powder printing operation; (4.2) If the surface roughness Ra of the titanium alloy sample after the heating treatment is greater than 1.3 μm, a pressing plate is used for flattening once, and the surface roughness of the titanium alloy sample after flattening is measured. In the n-times flattening treatment: (4.2.1) If the surface roughness Ra of the titanium alloy sample after the mth flattening (m<n) is greater than 1.3 μm, the nth flattening operation is performed by using a pressing plate, and the surface roughness Ra of the titanium alloy sample after the nth flattening treatment is determined as follows: (4.2.1.1) If the surface roughness Ra of the titanium alloy sample after the nth flattening is ≥ 1 μm, step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after the flattening treatment is < 1 μm, then the flattening is stopped and the powder printing operation is continued; (4.2.1.2) If the surface roughness Ra of the titanium alloy sample after the nth flattening is less than 1 μm, stop flattening and continue the powder printing operation; (4.2.2) If the surface roughness of the titanium alloy sample after the mth (m<n) flattening is 1.3μm≥Ra≥1μm, the roller flattening method is selected to perform nm times of flattening treatment, and the surface roughness Ra of the titanium alloy sample after the nth flattening treatment is determined as follows: (4.2.2.1) If the surface roughness Ra of the titanium alloy sample after the nth flattening is ≥ 1 μm, the step (3) needs to be repeated until the surface roughness Ra of the titanium alloy sample after the flattening treatment is < 1 μm, then the flattening is stopped and the powder printing operation is continued; (4.2.2.2) If the surface roughness Ra of the titanium alloy sample after the nth flattening is less than 1 μm, stop the flattening and continue the powder printing operation.

3. The method for manufacturing a titanium alloy part according to claim 1, characterized in that: Before heating the titanium alloy sample, it is necessary to determine the optimal parameter combination of the titanium alloy sample during the laser heating process. The steps for determining the optimal parameter combination are as follows: Determine the parameters that affect the laser heating process, which are laser power, scanning speed, and printing layer thickness; The laser power range, scanning speed range and printing layer thickness range of the titanium alloy samples under printing were obtained, and the optimal parameter combination among the three parameters of laser power, scanning speed and printing layer thickness during the laser heating process was obtained through the orthogonal experimental method.

4. The method for manufacturing a titanium alloy part according to claim 1, characterized in that: The number of times of the laser heating is in the range of 1-8 times; the number of times of the flattening operation is in the range of 2-9 times.

5. The method for manufacturing a titanium alloy part according to claim 1, characterized in that: It also includes the following steps: during printing, the number of layers of the titanium alloy to be prepared is divided into a layer and b layer, a:b=2:1~4:3; and the specified number of layers before printing the a layer is less than the specified number of layers after printing the b layer.

6. The method for manufacturing a titanium alloy part according to claim 1, characterized in that: During the printing process, the particle size of the titanium alloy powder is 15μm-45μm, the laser power is 100-400W, the laser spot diameter is 50μm-100μm, and the scanning speed is 500-3000mm / s; and / or Preheat the substrate before printing at a temperature of 180°C-220°C; and / or Argon gas needs to be introduced for gas protection during printing, and the flow rate of the introduced argon gas is 5L / min-20L / min.

7. A titanium alloy manufacturing device, characterized in that: The titanium alloy part is prepared by the method for manufacturing a titanium alloy part according to any one of claims 1 to 6, which comprises: A frame (1), wherein the frame (1) is provided with a powder bin (11) and a molding bin (12) which are independent of each other, the powder bin (11) and the molding bin (12) are both movable along the vertical direction of the frame (1), and a substrate (121) for printing is installed in the molding bin (12); a powder scraping assembly, the powder scraping assembly being mounted on a side of the frame (1) close to the powder bin (11), the powder scraping assembly being moved from the powder bin (11) to the molding bin (12) to spread the powder in the powder bin (11) onto the base plate (121) of the molding bin (12); A flattening assembly, comprising a roller flattening assembly and a pressure plate flattening assembly, wherein the pressure plate flattening assembly is mounted on the frame (1) and is located directly above the substrate (121), and the pressure plate flattening assembly is used to vertically pressurize the titanium alloy sample on the substrate (121) from top to bottom; the roller flattening assembly is mounted on the powder scraping assembly, and the roller flattening assembly is used to roll and pressurize the titanium alloy sample on the substrate (121); a laser source, the laser source being located above the forming chamber (12), the laser source being used to heat the titanium alloy powder spread on the substrate (121); A control system is used to control the movement of the powder scraping component, the flattening component and the laser source respectively.

8. The manufacturing equipment of titanium alloy parts according to claim 7, characterized in that: The powder scraping assembly comprises a driving member 1 and a scraper (2); the scraper (2) is slidably mounted on the frame (1); the driving member 1 drives the scraper (2) to move back and forth between the powder bin (11) and the molding bin (12); the scraper (2) is a soft scraper; an angle is provided between the length side of the scraper (2) and the length side of the titanium alloy sample, and the range of the angle is 5° to 45°.

9. The manufacturing equipment of titanium alloy parts according to claim 7, characterized in that: The roller flattening assembly comprises a second driving member and a roller (3), wherein the second driving member is connected to the roller (3) and is used to adjust the height of the roller (3).

10. The manufacturing equipment of titanium alloy parts according to claim 7, characterized in that: A driving member three (13) is also provided below the powder bin (11), and a driving member four (14) is also provided below the molding bin (12); the driving member three (13) drives the powder bin (11) to move along the vertical direction of the frame (1) to adjust the thickness of the powder layer entering the molding bin (12); the driving member four (14) drives the molding bin (12) to move along the vertical direction of the frame (1) to adjust the height of the base plate (121); and / or A plurality of titanium alloy samples can be printed on the substrate (121) at one time, the plurality of titanium alloy samples are staggered, and the minimum distance between two adjacent titanium alloy samples is greater than or equal to 2 cm.

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