Integrated high-precision additive manufacturing method for multi-channel bearing rack

Abstract

The invention discloses an integrated high-precision additive manufacturing method for a multi-channel force-bearing rack, which comprises the following steps: firstly, based on a design model of the multi-channel force-bearing rack, designing an inner runner structure of the rack into a water drop shape with equal area, forming a powder cleaning hole communicated with the outside in the inner runner, and forming a powder cleaning process port at the outlet position of the inner runner; the forming direction of the rack is determined, a solid support is added to the rack body part with the included angle smaller than the forming direction angle with the base plate, and an initial manufacturing model of the rack is formed; afterwards, the shrinkage amount is preset for the manufacturing initial model of the rack, a grid support is added to the outer portion of a runner in the rack, and the included angle between the runner and the base plate is smaller than the forming direction angle, so that a manufacturing model of the rack is formed; and finally, manufacturing and processing by adopting a selective laser melting forming process, and cutting to remove the substrate and the solid support. According to the invention, through the structural redesign of the rack design model and the selective laser melting forming process design, the problem of integral manufacturing of the rack is solved.

Description

TECHNICAL FIELD

[0001] The application relates to a kind of whole high-precision additive manufacturing methods of multi-channel force frame, belong to metal additive manufacturing technical field. BACKGROUND

[0002] Multi-channel force frame mainly undertakes two functions of engine mechanical installation and propellant supply, currently mainly adopts split structure forming, realizes the mechanical installation of thrust chamber and storage tank through frame, realizes the delivery of gas, oxidant, fuel through independent pipe structure, after split manufacturing, welding forming is carried out again, there are problems such as complex process flow, large number of components, non-compact structure and poor reliability. In recent years, with the development of aerospace liquid power system to high compactness and extreme lightweight, it is necessary to realize the installation of dozens of engines and the welding of propellant supply pipeline in a smaller space, so the traditional split processing scheme is difficult to realize, and the flow channel needs to be built-in inside the frame to realize the integrated manufacturing of multi-channel force frame.

[0003] Laser selective melting forming technology (SLM for short) is not affected by the complexity of components and the difficult processing performance of materials, and can directly prepare metal components with complex shape, high precision, dense structure and stable performance, which has been deeply applied in the field of aerospace, and can effectively solve the integrated manufacturing problem of multi-channel force frame. SUMMARY

[0004] The technical problem solved by the application is to overcome the shortcomings of the prior art, and a whole high-precision additive manufacturing method of multi-channel force frame is provided, which solves the problem of whole manufacturing of the frame through structural redesign of the frame design model and laser selective melting forming process design.

[0005] The technical solution of the application is:

[0006] A whole high-precision additive manufacturing method of multi-channel force frame comprises:

[0007] Based on the design model of multi-channel force frame, the flow channel structure in the frame is designed as an equal-area water droplet shape, a powder cleaning hole is arranged on the inner flow channel and communicates with the outside, and a powder cleaning process hole is arranged at the outlet position of the inner flow channel; the forming direction of the frame is determined, and entity support is added to the frame body with an angle smaller than the angle of the forming direction with the substrate to form a manufacturing initial model of the frame;

[0008] According to the design size of the frame, the manufacturing initial model of the frame is pre-set with a shrinkage amount, and grid support is added to the outside of the inner flow channel of the frame with an angle smaller than the angle of the forming direction with the substrate to form a manufacturing model of the frame;

[0009] Based on the rack-based manufacturing model, the laser selective melting forming process is used to manufacture the rack with substrate;

[0010] After the rack with substrate is sequentially cleaned and stress treated, the substrate and the solid support are cut and removed.

[0011] Further, TC4 titanium alloy is used as the forming material, and the laser selective melting forming process parameters of the rack and the solid support are as follows: the laser power is 250W-290W, the scanning speed is 1000mm / s-1300mm / s, the scanning interval is 0.08mm-0.12mm, and the phase angle is 67°; the laser selective melting forming process parameters of the grid support are as follows: the laser power is 100W-120W, the scanning speed is 500mm / s-600mm / s, the scanning interval is 0.08mm-0.12mm, and the phase angle is 67°.

[0012] Further, when the outer contour of the rack is greater than 400mm, 0.3-0.4% shrinkage is preset in the X and Y directions, and 0.15%-0.2% shrinkage is preset in the Z direction; when the outer diameter of the rack is not more than 400mm, 0.2-0.3% shrinkage is preset in the X and Y directions, and 0.1%-0.15% shrinkage is preset in the Z direction.

[0013] Further, when the length of the inner flow channel of the rack exceeds 200mm, a powder cleaning hole is provided which is connected to the outside, and the powder cleaning hole is circular in shape with a diameter not exceeding Φ6mm.

[0014] Further, the inner flow channel structure of the rack is water-drop-shaped, and the top corner is less than R3mm.

[0015] Further, the method for cutting and removing the substrate and the solid support is as follows: high-speed reciprocating wire spark discharge cutting is used, the pulse waveform is rectangular pulse, the pulse width is set to 20μs-45μs, the pulse interval is 150μs-200μs, and the current is 5A-7A.

[0016] Further, the direction of the rack at an angle of 45° with the horizontal direction is selected as the forming direction of the rack.

[0017] Further, the laser selective melting forming process is used to manufacture under an inert atmosphere, and the oxygen content in the atmosphere during the forming process is less than 500ppm.

[0018] Further, during powder cleaning, a compressed air pipe is connected to the powder cleaning process port, and the vibration platform is adjusted in angle, and the time is not less than 5h, and the powder on the outer surface, the inner cavity and the flow channel of the rack is blown away.

[0019] Further, the stress relief heat treatment parameters are as follows: the temperature is 800±5℃, the holding time is 2h-5h, and the air cooling is performed.

[0020] The present application has the following advantages compared with the prior art:

[0021] (1) The present application provides a kind of integrated high-precision additive manufacturing method of multi-channel force bearing frame, by laser selective melting forming technology can not be limited by structure, according to three-dimensional model directly forms the frame that engine mounting bracket and propellant pipeline are integrated, compact structure, simple process, short processing cycle, and greatly improve reliability.

[0022] (2) The present application provides a kind of integrated high-precision additive manufacturing method of multi-channel force bearing frame, by designing reasonable shrinkage ratio, the precision of frame can reach ±0.2 / 100mm. Through process parameter control, realize that frame internal organization structure is dense, grain is small, and mechanical property is excellent, greatly improve the use performance of frame.

[0023] (3) The present application provides a kind of integrated high-precision additive manufacturing method of multi-channel force bearing frame, by optimizing the design to the flow passage structure of frame, and adding powder removal hole, high-precision, high-surface quality frame flow passage can be realized without support self-forming, and effectively improve the powder removal efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not intended to limit the present application thereto. Moreover, the use of the same reference symbols in different drawings indicates similar or identical items. In the drawings:

[0025] Figure 1 It is a schematic diagram of the frame channel structure of the embodiment of the present application;

[0026] Figure 2 It is a schematic diagram of the frame flow passage powder removal port distribution of the embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of the frame macroscopic surface of the embodiment of the present application;

[0028] Figure 4 It is a flow chart of the integrated high-precision additive manufacturing method of multi-channel force bearing frame of the embodiment of the present application. DETAILED DESCRIPTION

[0029] Exemplary embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0030] The application proposes a whole high-precision additive manufacturing method of a multi-channel force-bearing rack, as shown in the accompanying drawings, comprising: Figure 4

[0031] Step one, rack model redesign

[0032] 1) Establish the rack model

[0033] According to the design requirements of the rack, use modeling software such as UG or Pro / E to design a multi-channel force-bearing rack model, the rack contour size is 600mm×200mm×300mm, and 3 flow channels are distributed inside. The cross section of the traditional manufacturing flow channel is generally circular, see Figure 1 (a), due to the limitation of additive manufacturing process, the top surface of the circular and rectangular flow channel will collapse during forming, resulting in forming failure. In order to realize high-quality self-supporting forming of the flow channel, the flow channel cross section of the flow and distribution rack is designed as an equal-area water droplet shape, see Figure 1 (b), to avoid the collapse of the molten pool during printing, resulting in forming failure, at the same time, improve the angle of the inner surface with the printing direction, set it to 45°, the top round angle is less than R3, obtain the inner flow channel with high surface quality. At the same time, in order to ensure the powder removal effect and efficiency, 2 powder removal holes are arranged on the inner flow channel of the rack, which are connected with the outside, the powder removal ports are evenly arranged on the flow channel, the powder removal port size is Φ6, the shape is circular, and the specific position is shown in Figure 2 .

[0034] 2) According to the structural characteristics of the rack, determine the forming direction, add solid support and powder removal process port

[0035] As shown in Figure 3 , according to the structural characteristics of the rack, select the direction of 45° angle between the main body of the rack and the horizontal direction as the forming direction of the rack, add solid support to the main body of the rack with an angle less than 45° with the substrate; Add powder removal process port to the flow channel outlet position.

[0036] 3) According to the size of the rack, the three-dimensional model of the rack with added solid support is pre-contracted as a whole, the shrinkage amount of X, Y direction is pre-set to 0.35%, and the shrinkage amount of Z direction is pre-set to 0.15%. Add grid support to the rack nozzle with an angle less than 45° with the substrate, and determine the three-dimensional model of the rack.

[0037] Step two, slice the three-dimensional model of the rack, and place the laser selective melting forming process parameters to obtain the processing program file

[0038] ​The rack model file is exported with an accuracy of 0.008 mm, and the model file of the rack is imported into the additive manufacturing auxiliary software, TC4 titanium alloy is used as the forming material, and the laser selective melting forming process parameters of the rack are as follows: laser power 250-290 W, scanning speed 900-1000 mm / s, scanning interval 0.08-0.12 mm, and phase angle 67°; the laser selective melting forming process parameters of the grid support are as follows: laser power 250-290 W, scanning speed 900-1000 mm / s, scanning interval 0.08-0.12 mm.

[0039] The laser selective melting forming of the rack is carried out in an inert atmosphere to obtain the rack with a substrate. Argon or nitrogen is used to form the inert atmosphere, and the oxygen content in the atmosphere during the forming process is required to be less than 500 ppm.

[0040] Step three, cleaning the powder in the outer surface, inner cavity and flow channel of the rack

[0041] The compressed air pipe is connected to the powder cleaning process port, and the vibration platform is used to change the angle and blow off the powder in the outer surface, inner cavity and flow channel of the rack for a long time (≥5 h) to ensure that the powder is completely cleaned.

[0042] Step four, stress relief heat treatment is carried out on the rack with the substrate, and the heat treatment system is 800 DEG C for 2-5 h, and the air is cooled.

[0043] Step five, after the heat treatment is completed, the substrate and the solid support are cut off.

[0044] High-speed reciprocating wire spark wire cutting is used, the pulse waveform is rectangular pulse, the pulse width is set to 20-45 mu s, the pulse interval is 150-200 mu s, and the current is 5-7 A; after the substrate and the support are removed, the wire cutting surface is polished to ensure smooth surface.

[0045] The present application realizes the integrated design and manufacturing of the multi-channel load-bearing rack integrating the engine mounting and propellant supply functions based on additive manufacturing, greatly shortens the processing cycle and improves the product reliability. At the same time, the powder cleaning efficiency of the rack is improved by more than 40% through reasonable design of the powder cleaning hole, the rack size accuracy is ensured through pre-set shrinkage compensation, the deviation is within ±0.2 / 100 mm, and a kind of integrated high-precision additive manufacturing method of multi-channel load-bearing rack is obtained.

[0046] The above-described embodiments are only preferred specific embodiments of the present application, and the usual changes and replacements made by those skilled in the art within the scope of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A method of integrated high precision additive manufacturing of a multi-pass force frame, characterized in that, The application relates to a method for manufacturing a multi-channel support frame. According to the design size of the frame, a shrinkage amount is preset to the manufacturing initial model of the frame, and a grid support is added to the outside of the inner flow channel of the frame with an angle smaller than the forming direction angle, so that a manufacturing model of the frame is formed; According to the manufacturing model of the frame, laser selective melting forming process is adopted to manufacture and process, so that the frame with the substrate is obtained; After the frame with the substrate is sequentially subjected to powder cleaning and stress heat treatment, the substrate and the entity support are cut and removed. TC4 titanium alloy is adopted as the forming material, and the laser selective melting forming process parameters of the frame and the entity support are as follows: the laser power is 250W-290W, the scanning speed is 1000mm / s-1300mm / s, the scanning interval is 0.08mm-0.12mm, and the phase angle is 67 degrees; the laser selective melting forming process parameters of the grid support are as follows: the laser power is 100W-120W, the scanning speed is 500mm / s-600mm / s, the scanning interval is 0.08mm-0.12mm, and the phase angle is 67 degrees.

2. A method of integrated high precision additive manufacturing of a multi-pass force-receiving frame according to claim 1, characterized in that, When the outer contour of the frame is greater than 400mm, the shrinkage amount of the X and Y directions is 0.3-0.4%, and the shrinkage amount of the Z direction is 0.15-0.2%; when the outer diameter of the frame is less than 400mm, the shrinkage amount of the X and Y directions is 0.2-0.3%, and the shrinkage amount of the Z direction is 0.1-0.15%.

3. A method of integrated high precision additive manufacturing of a multi-pass force-receiving rack according to claim 1, characterized in that, When the length of the inner flow channel of the frame exceeds 200mm, one powder cleaning hole penetrating the outside is arranged, and the powder cleaning hole is circular and has a diameter of not more than Phi 6mm.

4. A method of integrated high precision additive manufacturing of a multi-pass force-restraining frame according to claim 1, characterized in that, The inner flow channel structure of the frame is drop-shaped, and the top round angle is less than R3mm.

5. A method of integrated high precision additive manufacturing of a multi-pass force-restraining frame according to claim 1, characterized in that, The method for cutting and removing the substrate and the entity support is as follows: high-speed reciprocating wire spark discharge wire cutting is adopted, the pulse waveform is rectangular pulse, the pulse width is set to be 20-45mu s, the pulse interval is 150-200mu s, and the current is 5-7A.

6. A method of integrated high precision additive manufacturing of a multi-pass force-restraining frame according to claim 1, characterized in that, The direction with an angle of 45 degrees between the frame and the horizontal direction is selected as the forming direction of the frame.

7. A method of integrated high precision additive manufacturing of a multi-pass force-restraining rack according to claim 1, characterized in that, The laser selective melting forming process is adopted to manufacture and process under an inert atmosphere, and the oxygen content in the atmosphere is less than 500ppm during the forming process.

8. A method of integrated high precision additive manufacturing of a multi-pass force-restraining frame according to claim 1, characterized in that, During the powder cleaning, a compressed air pipe is connected to the powder cleaning process port, and the vibration platform is used to change the angle, and the time is not less than 5h, so that the powder on the outer surface, the inner cavity and the flow channel of the frame is blown away.

9. A method of integrated high precision additive manufacturing of a multi-pass force-restraining frame according to claim 1, characterized in that, The stress relief heat treatment parameters are as follows: the temperature is 800+ / -5 DEG C, the holding time is 2-5h, and the air cooling is performed.

10. A method of integrated high precision additive manufacturing of a multi-pass force- receiving frame according to claim 1, characterized in that, ​

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