Lattice configuration electric propulsion engine shell and 3D printing method thereof

Abstract

The invention relates to a lattice configuration electric propulsion engine shell and a 3D printing method thereof, belongs to the technical field of 3D printing, and solves the technical problems of long period and high cost in preparation of the lattice configuration electric propulsion engine shell. The engine shell comprises a shell windowing structure, an engine main force bearing frame, a pyramid-shaped lattice structure and a tetrahedron-shaped lattice structure, and the engine shell is provided with an engine outlet end cover mounting hole, an internal equipment mounting positioning groove, an engine outer wall equipment mounting hole, an engine base mounting hole and an engine tail end opening cover mounting hole. The 3D printing method comprises the steps of structural feature modeling, topological optimization design, dot matrix optimization design, 3D printing model design and 3D printing additive manufacturing. The 3D printing additive manufacturing method is used for 3D printing additive manufacturing of the lattice configuration electric propulsion engine shell.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of 3D printing, and particularly relates to a dot matrix configuration electric propulsion engine shell and a 3D printing method thereof. BACKGROUND

[0002] With the rapid development of space technology, space missions have put forward technical requirements of high specific impulse, high efficiency, long life, micro-thrust and high cost performance for the power system of a spacecraft. Different types of electric propulsion systems perfectly meet the above requirements and are widely used in engineering application fields such as attitude control, position keeping, resistance compensation, orbit transfer and deep space exploration of a spacecraft. The electric propulsion system applied to a space spacecraft has extremely strict requirements on volume and weight. According to statistics, the launch cost of a product on a satellite is 200,000 yuan per kilogram. Each gram of weight increase of the electric propulsion system will increase the cost of the power system and reduce the effective load of the satellite. Therefore, it is necessary to carry out lightweight structure design for the electric propulsion system.

[0003] The electric propulsion engine shell is a key structural component in the electric propulsion system and has the following functions: (1) meeting the installation support and fixing requirements of electric propulsion engine components (for example, the serial numbers 1-6 of the electric propulsion engine shell shown in Figs. 1-3 meet the installation support and fixing requirements of electric propulsion engine components), meeting the strength and stiffness requirements under working load; (2) having vibration and shock reduction and resistance requirements for different vibration and shock environments such as ground transportation, launch and on-orbit; (3) meeting other requirements, for example, some electric propulsion engines require the shell to have the function of shielding external electromagnetic radiation (for example, the outer wall lightening holes of the engine shell shown in Fig. 4 must be smaller than a certain fixed aperture value and be distributed at a certain interval, so that the engine shell has the function of shielding external electromagnetic radiation); and (4) other requirements. Figure 1 、 Figure 2 The existing electric propulsion engine shell widely adopts a frame beam type thin-walled stiffened structure (for example, the serial number 7 of the engine shell shown in Fig. 5), which is produced by machining. However, the existing electric propulsion engine shell has the following problems: (1) the strength and stiffness margins of many regions of this structure type are too large, lightweight is not good, and material utilization rate needs to be improved; (2) for small electric propulsion engines, various grooves, holes and other features need to be machined in the narrow space of the engine shell to meet the installation requirements. In the regions that are difficult to machine, special machining methods such as electric spark are often considered, which increases the manufacturing cycle and cost of the product. Figure 1 Figure 1 In order to overcome the long cycle and high cost of preparing the electric propulsion engine shell, the application provides a dot matrix configuration electric propulsion engine shell and a 3D printing method thereof. SUMMARY

[0004] In order to overcome the long cycle and high cost of preparing the electric propulsion engine shell, the application provides a dot matrix configuration electric propulsion engine shell and a 3D printing method thereof.

[0005] The technical solution adopted by the application to solve the technical problems is as follows: ​

[0006] A dot-matrix configuration electric propulsion engine shell 3D printing method, comprising the following steps:

[0007] Step S1, structure feature modeling

[0008] The dot-matrix configuration electric propulsion engine shell is divided into a non-design domain and a design domain, and the structure features of the design domain are modeled according to the engine component installation, support and fixing requirements and functional requirements, to obtain a design domain structure feature model.

[0009] Step S2, topology optimization design

[0010] The design domain structure feature model obtained in step S1 is used for topology optimization design. According to the optimization calculation result, secondary modeling is carried out to determine the engine main load-bearing frame and the secondary load-bearing area of the dot-matrix filling, to obtain a design domain structure feature secondary model.

[0011] Step S3, dot-matrix optimization design

[0012] The design domain structure feature secondary model obtained in step S2 is used to select the sub-unit types of the dot-matrix into pyramid-type dot-matrix structure dot-matrix units and tetrahedron-type dot-matrix structure dot-matrix units, and dot-matrix optimization design is carried out. According to the dot-matrix optimization design, a plurality of rounds of iterative calculations are carried out until the model structure meets the design requirements of the dot-matrix configuration electric propulsion engine shell.

[0013] Step S4, 3D printing model design

[0014] The model meeting the design requirements of the dot-matrix configuration electric propulsion engine shell is post-processed. A surface fitting algorithm is used to make the diameter of the dot-matrix rod system smooth and gradually change, and the dot-matrix and the solid structure continuously and gradually change and transition, and the intersection of the dot-matrix point system is smooth and transitions. A dot-matrix configuration electric propulsion engine shell design model is obtained.

[0015] Step S5, 3D printing additive manufacturing

[0016] The design model is converted into a 3D printing additive manufacturing file format, and a 3D printing additive manufacturing device is used to implement the 3D printing of the dot-matrix configuration electric propulsion engine shell.

[0017] In the above 3D printing method, in step S1, the non-design domain includes an engine outlet end cover mounting hole, an internal device mounting and positioning groove, a shell window structure, an engine outer wall device mounting hole, an engine base mounting hole, and an engine tail end port cover mounting hole. The design domain includes engine internal grooves, flow channels, and cavities. A machining allowance is reserved for the machining parts of the engine shell, and the machining parts include threaded holes.

[0018] In the above 3D printing method, step S3, dot-matrix optimization design further comprises:

[0019] The size range of the dot matrix unit, the diameter variation range of the dot matrix truss, and the dot matrix filling rate are taken as design variables, the structural strength, the stiffness, and the frequency corresponding to the low-order mode are taken as constraint conditions, and the minimum structural volume or the minimum weight is taken as a design target.

[0020] The 3D printing method, the step S4, the 3D printing model design further comprises:

[0021] According to the effect of the engine shell grid shielding electromagnetic radiation, the size range of the dot matrix unit is determined; and according to the 3D printing additive manufacturing process, the diameter variation range of the dot matrix truss is determined, so that the transition between the trusses is smooth and uniform.

[0022] The 3D printing method, in the step S5, the 3D printing additive manufacturing file format can be *.step format or *.stl format.

[0023] The 3D printing method, in the step S5, the 3D printing additive manufacturing adopts a laser selective melting method.

[0024] A dot matrix configuration electric propulsion engine shell comprises a non-design domain and a design domain. The non-design domain comprises an engine outlet end cover mounting hole, an internal device mounting positioning groove, an engine outer wall device mounting hole, an engine base mounting hole, an engine tail port cover mounting hole, and an engine main load-bearing frame; and the non-design domain comprises a dot matrix filled secondary load-bearing area.

[0025] The dot matrix filled secondary load-bearing area of the dot matrix configuration electric propulsion engine shell is composed of a pyramid type dot matrix structure and a tetrahedron type dot matrix structure.

[0026] The dot matrix configuration electric propulsion engine shell has the following beneficial effects:

[0027] A dot matrix configuration electric propulsion engine shell is based on the characteristics of small thrust and low load of an electric propulsion engine, under the premise of meeting the requirements of engine part installation support fixing, strength and stiffness under working load, further reducing the weight of the engine shell, improving the utilization rate of materials, shortening the manufacturing cycle and saving costs through mature 3D printing manufacturing process, improving the vibration damping and vibration resistance performance of the engine shell structure by using the impact resistance and energy absorption characteristics of the dot matrix structure, and using the dot matrix spatial topology structure to make the shell have the function of shielding external electromagnetic radiation.

[0028] A dot matrix configuration electric propulsion engine shell adopts an engine shell with dot matrix design, which has a hollow mesh spatial topology structure, electromagnetic waves can be reflected and scattered at the pore interface of the dot matrix material, and the effect of electromagnetic shielding can be achieved.

[0029] A dot matrix configuration electric propulsion engine shell 3D printing method, through topological optimization non-design domain division, ensures that the electric propulsion engine shell structure meets the engine part installation support fixing requirements.

[0030] A dot matrix configuration electric propulsion engine shell 3D printing method, through topological optimization and dot matrix optimization design, the main load-bearing frame and the dot matrix filled secondary load-bearing area are obtained, the rod system diameter of the dot matrix is smoothly changed and smoothly transitioned, the dot matrix and the solid structure are gradually changed and transitioned, and the structure is continuous, the dot matrix point system intersection is smoothly transitioned, the stress mutation is reduced under the condition of shell loading, and the stress distribution on the shell is more uniform.

[0031] A dot matrix configuration electric propulsion engine shell 3D printing method, the dot matrix design adopts a pyramid type and a tetrahedron type dot matrix structure, has the advantages of low material density, high compressive strength and strong impact protection ability, and has the characteristics of buffering and energy absorption. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is an existing technology engine shell axial side view;

[0033] Figure 2 is a semi-perspective view of the prior art engine shell;

[0034] Figure 3 is an engine shell axial side view of the embodiment of the present application;

[0035] Figure 4 is an engine shell bottom view of the embodiment of the present application;

[0036] Figure 5 is Figure 3 a local enlarged view of A in the figure.

[0037] The drawings show that: 1. Engine outlet end cover mounting hole, 2. Internal equipment installation positioning groove, 3. Shell window structure, 4. Engine outer wall equipment mounting hole, 5. Engine base mounting hole, 6. Engine tail end port cover mounting hole, 7. Shell stiffened structure, 8. Outer wall lightening hole, 9. Engine main load-bearing frame, 10. Pyramid type dot matrix structure, 11. Tetrahedron type dot matrix structure. DETAILED DESCRIPTION

[0038] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0039] Example 1

[0040] Topology optimization and 3D printing additive manufacturing technology have laid a solid foundation for the lightweight design of electric propulsion engine casings. Domestic and foreign 3D printing additive manufacturing manufacturers have provided a large number of products that can be used in mature models and commercial operations for many units in the aviation and aerospace fields, and have been used and verified in various engineering application scenarios.

[0041] Please see Figure 3 , Figure 4 , Figure 5 Taking a certain type of electric propulsion engine casing as an example, this paper describes in detail the specific implementation of a 3D printing method for a lattice-configured electric propulsion engine casing according to the present invention. First, before performing topology optimization, the engine outlet end cover mounting holes ( Figure 3 Serial number 1) Internal equipment installation positioning slot ( Figure 3 Serial number 2), Window structure of the shell ( Figure 3 Serial number 3), Engine outer wall equipment mounting holes ( Figure 3 Serial number 4), Engine base mounting holes ( Figure 3 Serial number 5), Engine tailgate mounting hole ( Figure 4 (Section 6) These structural features are divided into non-design domains. Sufficient machining allowance is reserved for features requiring machining, such as threaded holes. For internal slots, flow channels, cavities, and other structures that can meet the precision requirements of 3D printing additive manufacturing, they can be modeled according to the final required structural features to ensure that the mounting, support, and fixing requirements and functional requirements of engine components are met. Next, topology optimization design is carried out, and secondary modeling is performed based on the optimization calculation results to determine the main load-bearing frame (…). Figure 3 (Sequence number 9) and the secondary load-bearing area filled with lattice. Subsequently, lattice optimization design was carried out, and the sub-unit type of the lattice was selected as pyramid type ( Figure 5 Serial number 10) and tetrahedral type ( Figure 5No. 11) lattice unit, make full use of the advantages of low material density, high compressive strength, strong impact protection ability and the characteristics of buffer energy absorption of the lattice structure with pyramid type and tetrahedron type. With the size range of lattice unit, the diameter change range of lattice rod system, the lattice filling rate as the design variable, the structural strength, stiffness and the frequency corresponding to the low order mode as the constraint condition, the minimum structure volume or weight as the design target, multiple iteration calculation is carried out, and finally the best lattice configuration of engine shell structure meeting the design requirements is obtained. The size range of the lattice unit must be determined according to the effect of the final shell grid shielding electromagnetic radiation; the diameter change range of the lattice rod system is determined according to the process level of the 3D printing additive manufacturing technology, so as to ensure smooth and uniform transition between rod systems and avoid micro defects formed by 3D printing additive manufacturing. For the post-processing stage of lattice optimization results, modeling technology is very critical, and surface fitting algorithm needs to be used to ensure smooth and gradual change of the diameter of the rod system of the lattice, smooth transition of the lattice and the solid structure, smooth transition of the intersection points of the lattice, and finally the design model is obtained. The design model is converted into *.step format or *.stl format, which can be processed by the current common 3D printing additive manufacturing equipment.

[0042] 3D printing additive manufacturing technology mainly includes laser selective sintering technology, laser selective melting technology and electron beam selective melting technology. Compared with other additive manufacturing processes, the parts manufactured by laser selective melting technology have more accurate structural micro features and better surface quality, and laser selective melting technology has more advantages in details and complexity. The lattice configuration electric propulsion engine shell structure designed in the application selects laser selective melting technology for 3D printing additive manufacturing.

[0043] The application can be widely applied to the design of electric propulsion engine shell structure, and a load-bearing shell structure meeting the requirements of structural strength and stiffness, having excellent lightweight performance and good anti-vibration and vibration reduction function is obtained, which has wide engineering application prospect.

Claims

1. A method for 3D printing a lattice-configured electric propulsion engine casing, characterized in that, Includes the following steps: Step S1, Structural Feature Modeling: The lattice-configured electric propulsion engine casing is divided into a non-design domain and a design domain. The structural features of the design domain are modeled according to the requirements for engine component installation, support and fixation, and functional requirements, resulting in a structural feature model of the design domain. Step S2, Topology optimization design: Using the design domain structure feature model obtained in step S1, topology optimization design is carried out; Based on the optimization calculation results, secondary modeling was carried out to determine the main load-bearing frame (9) of the engine and the secondary load-bearing area filled by the lattice, and a secondary model of the structural features of the design domain was obtained. Step S3, Dot matrix optimization design: Using the secondary model of the design domain structure features obtained in step S2, the sub-unit types of the lattice are selected as pyramid lattice structure (10) lattice unit and tetrahedral lattice structure (11) lattice unit, and lattice optimization design is carried out. Based on the lattice optimization design, several rounds of iterative calculations were carried out until the model structure met the design requirements of the lattice configuration electric propulsion engine casing. Step S4, 3D printing model design: The model that meets the design requirements of the lattice configuration electric propulsion engine casing is post-processed; a surface fitting algorithm is used to make the diameter of the rod system of the lattice smooth and gradual, the lattice and the solid structure continuously and gradually transition, and the intersection of the point system of the lattice smooth; thus, the design model of the lattice configuration electric propulsion engine casing is obtained. Step S5, 3D printing additive manufacturing: The design model was converted into a 3D printing additive manufacturing file format, and 3D printing additive manufacturing equipment was used to carry out 3D printing of the lattice configuration electric propulsion engine casing.

2. The 3D printing method according to claim 1, characterized in that, In step S1, the non-design domain includes the engine outlet end cover mounting hole (1), the internal equipment mounting positioning groove (2), the housing window structure (3), the engine outer wall equipment mounting hole (4), the engine base mounting hole (5), and the engine tail end cover mounting hole (6); the design domain includes the engine internal slots, flow channels, and cavities; machining allowances are reserved for the machined parts of the engine housing, and the machined parts include threaded holes.

3. The 3D printing method according to claim 1, characterized in that, Step S3, the dot matrix optimization design, further includes: The design variables are the size range of the lattice elements, the diameter variation range of the lattice rod system, and the lattice filling rate. The constraints are the structural strength, stiffness, and the frequencies corresponding to the low-order modes. The design objective is to minimize the structural volume or weight.

4. The 3D printing method according to claim 1, characterized in that, Step S4, the 3D printing model design, further includes: Based on the effect of the engine housing mesh in shielding electromagnetic radiation, the size range of the lattice unit is determined; based on the 3D printing additive manufacturing process, the diameter variation range of the lattice rod system is determined to ensure a smooth and uniform transition between the rod systems.

5. The 3D printing method according to claim 1, characterized in that, In step S5, the 3D printing additive manufacturing file format can be either *.step or *.stl.

6. The 3D printing method according to claim 1, characterized in that, In step S5, 3D printing additive manufacturing uses laser selective melting.

7. A lattice-configured electric propulsion engine casing, characterized in that, The housing includes a non-designed domain and a designed domain; the non-designed domain includes an engine outlet end cover mounting hole (1), an internal equipment mounting positioning groove (2), an engine outer wall equipment mounting hole (4), an engine base mounting hole (5), an engine tail end cover mounting hole (6), and an engine main load-bearing frame (9); the non-designed domain includes a secondary load-bearing area filled with a lattice.

8. The lattice-configured electric propulsion engine housing according to claim 7, characterized in that, The secondary load-bearing region filled by the lattice is composed of a pyramid-shaped lattice structure (10) and a tetrahedral lattice structure (11).

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