CN111274678B - Manufacturing method of space electronic case - Google Patents
Manufacturing method of space electronic case Download PDFInfo
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- CN111274678B CN111274678B CN202010032590.1A CN202010032590A CN111274678B CN 111274678 B CN111274678 B CN 111274678B CN 202010032590 A CN202010032590 A CN 202010032590A CN 111274678 B CN111274678 B CN 111274678B
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- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
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Abstract
The invention relates to a manufacturing method of an aerospace electronic case, belongs to the technical field of case research and development design, and solves the problems that in the design process of the conventional aerospace electronic case: (1) The reliability and the precision of the product are ensured by means of manual calculation, and the efficiency and the reliability are low; (2) The software design process structure design and reliability analysis are separated, the process is complex, and the efficiency is low. The method comprises the following steps: s1: establishing a size parameterization calculation model, and preliminarily calculating the size tolerance of the case; s2: carrying out thermal analysis of the chassis and parameterized simulation of the insertion and extraction force analysis of the module box; s3: calculating the packaging layout of the electronic device and the plugging angle and the offset of the module box; s4: calculating to obtain the dimensional tolerance of the chassis; s5: and manufacturing the electronic chassis according to the dimensional tolerance. The invention combines the structural design and reliability analysis of the design process of the electronic case, so that the research and development design of the electronic case is easy to operate, and the design and manufacturing efficiency of the electronic case is improved.
Description
Technical Field
The invention relates to the field of research and development design of cabinets, in particular to design of an aerospace electronic cabinet, and particularly relates to a manufacturing method of the aerospace electronic cabinet.
Background
With the rapid development of Computer technology, computer mechanics and other disciplines, CAD (Computer Aided Design) and CAE (Computer Aided Engineering) technologies have appeared, and their appearance improves the Design efficiency and reliability of products.
Although the existing drawing software and finite element analysis software have strong functions and shorten the product development period, the existing general software is not specially designed for the development of electronic equipment, and the structural design and reliability analysis of the product are separated from each other. Because the experimental cost is high, the thermal design at present mainly adopts CAE software to verify the thermal design, but most product research personnel rarely contact thermal design and mechanics theory, and the CAE operation interface is complex, so the time cost for learning is high. In the research and development stage of products, thermal design is basically a cycle of 'design-simulation analysis-improved design', and more repetitive work is needed; meanwhile, the existing CAD/CAE software model is difficult to convert, and the difficulty of improving the design level is increased.
In order to promote the development of aerospace industry in China, the research and development of the aerospace electronic case is short in required period, high in efficiency and high in reliability and precision of products, however, in the research and development process of the existing aerospace electronic case, the reliability and precision of the products are mostly ensured through manual calculation, and the calculation process is complex, low in efficiency and low in reliability; even if software is adopted to carry out research and development design on the space electronic chassis, the problems of mutual separation of structural design and reliability analysis, complex design and check process and low efficiency also exist, and the software has higher professional literacy requirements on designers.
Disclosure of Invention
In view of the foregoing analysis, an embodiment of the present invention is directed to a method for manufacturing an avionics chassis, so as to solve the problems of the existing design process of the avionics chassis: (1) The reliability and the precision of the product are ensured by means of manual calculation, and the efficiency and the reliability are low; (2) The software design process structure design and reliability analysis are separated, the process is complex, and the efficiency is low.
The purpose of the invention is mainly realized by the following technical scheme:
a method of manufacturing an avionics chassis, the method comprising the steps of:
s1: establishing a dimensional parameterization calculation model, and preliminarily calculating the dimensional tolerance of the case;
s2: carrying out cabinet thermal analysis and module box insertion and extraction force analysis parameterized simulation;
s3: calculating the packaging layout of the electronic device and the plugging angle and the offset of the module box;
s4: calculating to obtain the size tolerance of the chassis;
s5: and manufacturing the electronic chassis according to the dimensional tolerance.
Further, in S1, the parameterization calculation refers to obtaining a model surface feature and a dimension set by labeling a dimension tolerance in a three-dimensional software through human-computer interaction, searching a dimension chain, and automatically calculating a dimension tolerance of the closed loop.
Further, the S1 step includes:
s1.1: marking the dimensional tolerance of the assembly body or the part;
s1.2: obtaining dimension information marked by dimension tolerance and establishing a dimension information set;
s1.3: determining a closed ring, and selecting the end face of the closed ring;
s1.4: acquiring a size chain where the closed ring is located according to the size information set and the end face of the closed ring;
s1.5: and calculating the size of the closed loop by adopting a loop method according to the acquired size chain.
Further, in S1.1, the content of the dimensional tolerance label is a basic size, an upper deviation, a lower deviation, and a size annotation, and the dimensional tolerance label is labeled in a surface-to-surface manner.
Further, in S1.4, a size chain loop search is used to obtain a size chain in which the closed ring is located, where the size chain loop search refers to a process of returning from one end face of the closed ring to the other end face of the closed ring through a group of ordered component rings.
In S1.5, the loop method is to determine the increase or decrease of the component ring based on the difference between the closed ring direction and the component ring direction.
Further, the step S2 includes:
s2.1: parameterizing the mould material data;
s2.2: parameterizing model size data;
s2.3: parameterizing initial solution parameters of the model;
s2.4: the model mesh partition size is parameterized.
Further, the step in S3 includes:
s3.1: loading a parameterized plug-in;
s3.2: inputting data parameters on a parameterized interface for solving;
s3.3: and judging whether the solving result meets the requirement, if so, performing S4, and otherwise, modifying the data parameters and performing S3.2.
Further, in S3.1, the parameterized plug-in is an ACT plug-in for the chassis thermal analysis and module box insertion and extraction force analysis parameterized simulation procedure established in S2.
Further, the step S4 includes:
s4.1: updating the design size of the case according to the solving result of S3;
s4.2: and recalculating dimensional tolerances of all parts of the chassis.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
(1) By establishing a dimensional calculation model, the surface characteristics and the size set of the model are obtained, a size chain is searched by combining a search algorithm, and the size of the dimensional tolerance of the closed ring is automatically calculated, so that a large amount of repeated manual work for calculating the dimensional tolerance is avoided, and the calculation efficiency and the calculation accuracy are improved;
(2) An Application Customization Toolkit (ACT) plug-in is formed by establishing a case thermal analysis and module box plugging force analysis parameterized simulation flow, and in the aerospace electronic case design process, under the condition that data is continuously changed, all parameters are required to be changed again on a parameterized interface without modeling simulation again, so that the parameterized plug-in is convenient to operate and use, and the simulation efficiency is improved;
(3) The traditional manual calculation of the dimension chain has large workload, and particularly has low calculation efficiency when the marked dimension and the coordinate axis have certain angles;
(4) The method comprises the steps of establishing a dimensional parameterized calculation model and a dimensional tolerance of the chassis, analyzing an ACT plug-in a parameterized simulation process according to established chassis thermal analysis and module box plugging force, calculating the packaging layout of the electronic device and the plugging angle and the offset of the module box, obtaining the dimensional tolerance of the chassis, combining the structural design and the reliability analysis of the design process of the electronic chassis, being easy to operate and improving the design and manufacturing efficiency of the electronic chassis.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a flow chart of a method of manufacturing an avionics chassis;
FIG. 2 is a schematic diagram of the overall structure of an avionics chassis;
FIG. 3 is a schematic diagram of a module case of the avionics chassis;
FIG. 4 is a simplified model of an avionics chassis;
FIG. 5 shows the gridding results of the avionics chassis;
FIG. 6 is a temperature field cloud of an avionics chassis;
FIG. 7 is a module box simulation model of an avionics chassis;
FIG. 8 is a block diagram of the modular case plug components of the avionics chassis;
FIG. 9 shows the results of the module box meshing for the avionics chassis;
FIG. 10 shows simulation results of inserting and pulling the module box of the avionics chassis.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention and not to limit its scope.
The invention discloses a method for manufacturing a space electronic chassis, which comprises the following steps as shown in figure 1:
s1: and drawing a three-dimensional model of the electronic case assembly body or the part by using SolidWorks, establishing a dimensional parameterization calculation model, and preliminarily calculating the dimensional tolerance of the case. The parameterization calculation means that dimensional tolerance is marked through man-machine interaction in three-dimensional software SolidWorks, a dimension chain is searched by acquiring surface features and a dimension set of the model and combining a search algorithm, and the dimensional tolerance of the closed ring is automatically calculated.
Specifically, S1: establishing a dimensional parameterization calculation model, and primarily calculating the dimensional tolerance of the case, wherein the dimensional parameterization calculation model comprises the following steps of:
s1.1: and (5) marking the dimensional tolerance of the assembly or the part. And marking the dimensional tolerance of the known component ring by using a DimXpert function of SolidWorks and using position dimension and size dimension options, wherein the marked content comprises basic dimensions, upper and lower deviations and dimension notes, and the marking mode adopts surface-to-surface marking. It should be noted that the labeling mode cannot be labeled by other modes except the surface-to-surface labeling; when the dimension tolerance is marked, marking the position dimension, wherein the tolerance/precision column selects bilateral type tolerance, the marking dimension text column can add annotation to the dimension in a self-defining way and cannot delete any content in the marking dimension text frame, otherwise, the displayed annotation is incomplete, and the annotation is directly added behind the default content; and (4) marking the sizes, wherein the sizes are the same as the positions and the sizes, the tolerance/precision column selects a bilateral tolerance type, the text column for marking the sizes can mark annotations, the existing content in the text frame for marking the sizes cannot be deleted, and the annotations are directly added behind the default content.
S1.2: and obtaining the dimension information marked by the dimension tolerance and establishing a dimension information set. Traversing S1.1 labeled dimensions and adding them into VB (Visual Basic) dictionary container to build dimension information set.
S1.3: determining a closed ring, and selecting the end face of the closed ring. And the man-machine interaction designates the starting end face and the ending end face of the closed ring.
S1.4: and obtaining a size chain where the closed ring is located through an algorithm according to the size information set and the end face of the closed ring. It should be noted that, the size chain in which the closed ring is located is obtained by using size chain loop search, which is a process of returning from one end face of the closed ring to the other end face of the closed ring through a group of ordered component rings. The traditional method for manually calculating the dimension chain has large workload, and particularly has low calculation efficiency when the marked dimension and the coordinate axis have a certain angle.
Specifically, the step of S1.4 includes:
s1.4.1: and taking the initial end face of the closed ring as an initial face, traversing a dimension information set in the dictionary, acquiring dimension marks and faces related to the dimension marks, and comparing whether the faces related to the dimension marks are in a superposition and coaxial relationship with the initial end face. If the superposition and coaxial relation exists, adding the traversed first dimension meeting the requirement into a linked list structure and deleting the dimension from the dictionary, and if the superposition and coaxial relation does not exist, the condition that the dimension marked by the S1.1 is incomplete and cannot be calculated is shown.
S1.4.2: and (4) acquiring a surface which is added into the S1.4.1 and has no coincidence and coaxial relation with the initial surface in the size of the chain table, and judging whether the surface has coincidence and coaxial relation with the terminating end surface of the closed ring. If the superposition and the coaxial relation exist, the size chain search is completed, and the size chain is searched; if the coincidence and coaxial relation does not exist, judging whether the dimension exists in the dictionary, if not, judging that the dimension marking is incomplete, and ending the search, if so, continuing to step S1.4.1, taking the surface as a starting surface, traversing the dimension information set in the dictionary again, adding the information meeting the conditions into the user-defined dimension chain array linked list, deleting the dimension from the dictionary, and searching downwards by the same method.
It should be noted that, if there is a case of a broken circuit in the search process, that is, there is a size in the dictionary, but the size of the array linked list to which the user-defined size is added most recently cannot be searched for its next associated size, it is indicated that the size is a part of the size chain, the size added to the array linked list needs to be deleted, and the step s1.4.1 is repeated again from the previous associated size of the size to start the search.
S1.5: and calculating the size of the closed loop by adopting a loop method according to the obtained size chain. If S1.4 can normally search a dimension chain, the increase and decrease of the component ring are determined by adopting a loop method, namely the difference between the closed ring direction and the component ring direction is determined according to the dimension chain, wherein the closed ring direction refers to the condition that the terminating surface points to the starting surface, the component ring in the same direction as the closed ring direction is a decrease ring, and the component ring in the same direction as the closed ring direction is an increase ring.
In the embodiment, the dimensional calculation model is established to obtain the surface characteristics and the dimension set of the model, the dimension chain is searched by combining the search algorithm, and the dimension tolerance of the closed ring is automatically calculated, so that a large amount of repeated manual work for calculating the dimension tolerance is avoided, and the calculation efficiency is improved.
S2: and carrying out case thermal analysis and plug-pull force analysis parameterized simulation on the module box. It should be noted that the parameterized simulation process of chassis thermal analysis and insertion and extraction force analysis of the module box refers to initially establishing a simulation process of chassis thermal analysis and insertion and extraction force analysis of the module box, then parameterizing relevant parameters affecting chassis thermal analysis and insertion and extraction force analysis and providing a uniform parameter input interface, and implementing parameterization by combining an XML (eXtensible Markup Language) text and a Python script.
Specifically, S2: carrying out case thermal analysis and module box insertion and extraction force analysis parameterized simulation, comprising the following steps:
s2.1: parameterizing the mode-type material data. Parameterizing the material according to different material parameters at different positions, and parameterizing the material heat conductivity coefficient and the material density aiming at the case thermal analysis; the material density, elastic modulus, poisson's ratio, and yield strength were parameterized for the cartridge insertion and extraction force analysis. Considering that a Printed Circuit Board (PCB) Board and copper are used, equivalent thermal conductivity is calculated according to the copper content of the upper cover assembly and the motherboard assembly, and a default material adopted by other parts of the chassis is aluminum alloy.
S2.2: parameterizing model size data. The size affects the insertion and extraction force of the cartridge and the results of the thermal analysis of the chassis, which needs to be parameterized. The machine case thermal analysis is mainly characterized in that the position of a heat source inside the module box and the size and the number of heat dissipation grooves of the box body are parameterized, and the XY offset and the offset angle of the module box are parameterized according to the insertion and extraction force analysis.
S2.3: and (5) parameterizing initial solution parameters of the model. Parameterization is carried out on the power and the ambient temperature of electronic devices packaged in the module box aiming at thermal analysis of the chassis, and the parameterization is respectively carried out on the friction force between the module box main body and a box guide rail and the friction force between a bolt at the lower end of the module box and a socket when the friction force of different contact areas of the insertion and extraction force analysis module box and the box is different.
S2.4: the model mesh partition size is parameterized. The grid division influences the precision of a simulation result, parameterization is needed, the box body part is a main heat dissipation area aiming at the thermal analysis of the chassis, and the relative heat dissipation capacity of an air medium is smaller, so that the box body part and the air medium are parameterized respectively; for the insertion and extraction force analysis, the contact area and the non-contact area are respectively divided into grids and parameterized.
In the embodiment, the ACT plug-in is formed by establishing a case thermal analysis and module box plugging force analysis parameterized simulation flow, and in the aerospace electronic case design process, under the condition that data is continuously changed, all parameters are required to be changed again on a parameterized interface without modeling simulation again, so that the parameterized plug-in is convenient to operate and use, and the simulation efficiency is improved.
S3: and calculating the packaging layout of the electronic device and the plug angle and the offset of the module box according to the parameterized simulation process of the thermal analysis of the chassis and the plug force analysis of the module box. It should be noted that, the step refers to calculating the package layout of the electronic device and the insertion and extraction angle and offset of the module box by continuously changing the relevant parameters through the simulation parameterization process established in S2.
In this embodiment, S3: calculating the packaging layout of the electronic device and the plugging angle and the offset of the module box, and comprising the following steps of:
s3.1: and loading S2 the parameterized plug-in. And loading the case thermal analysis and module box plugging force analysis parameterized simulation process ACT plug-in established in the step S2 into an ANSYS workbench.
S3.2: and inputting data parameters on the parameterized interface for solving. And operating the ACT plug-in, and inputting the required parameters on the parameterized interface to solve.
S3.3: analyzing the solving result to judge whether the requirement is met, if so, carrying out S4, otherwise, modifying the parameters to carry out S3.2.
It should be noted that the basis for judging whether the solution result meets the requirement is as follows: under the condition of determining the power and the ambient temperature of a heat source, optimizing the surface treatment process of the case and the structural size of the case, such as a heat dissipation groove or a heat source distribution position, or optimizing the power and the position of the heat source under the condition of determining the surface treatment process and the structural size of the case, so that the highest temperature of the heat source meets the rated temperature, and the smaller the highest temperature is, the better the highest temperature is; meanwhile, the maximum equivalent stress of the module box insertion and extraction force meets the requirement of the yield strength of the used material.
S4: and calculating again to obtain the dimensional tolerance of the chassis according to the packaging layout of the electronic devices and the plugging angle and the offset of the module box. It should be noted that, this step is to update the chassis model through the solution obtained in step S3, and recalculate the corresponding dimensional tolerance of the chassis using the plug-in obtained in step S1.
Specifically, S4: calculating to obtain the size tolerance of the chassis, wherein the steps comprise:
s4.1: and updating the design size of the case according to the solving result. And updating the case model by adopting a CAD/CAE interface according to the solving result of the S3.
S4.2: and calling the size chain of S1 to automatically generate plug-in units to recalculate the dimensional tolerance of each part of the chassis.
In the embodiment, the method comprises the steps of calculating the packaging layout of the electronic device and the plug-in angle and the offset of a module box by establishing a dimensional parameterized calculation model and calculating the dimensional tolerance of a chassis and analyzing a parameterized simulation process ACT plug-in according to the established thermal analysis of the chassis and the plug-in force of the module box; and the dimensional tolerance of the electronic case is obtained, the structural design and reliability analysis in the design process of the electronic case are combined, the operation is easy, and the design efficiency of the electronic case is improved.
S5: and performing production and manufacturing of the electronic chassis according to the dimensional tolerance of the chassis.
Specifically, the S5 step includes:
s5.1: compiling a product production and processing flow according to the dimensional tolerance of the case;
the front stage of the production and processing flow of the product is a part process and the rear stage of the production and processing flow of the product is a finished product process, wherein the part process comprises mechanical processing and surface treatment of all components of the case; the finished product process comprises finished product assembly, self-inspection, product inspection and packaging and warehousing.
S5.2: issuing a part production plan according to a product processing flow, and compiling a part processing flow according to a part processing technology;
the processing flow of each part of the case is as follows: general milling, numerical control milling, deburring, cleaning, rotary electroplating, conductive oxidation, paint spraying, drying, inspection and next step (finished product assembly); it should be noted that the box body needs to be threaded between the numerical control milling and the deburring.
S5.3: finishing the part processing, entering a finished product assembling procedure, and compiling into a finished product assembling flow;
the finished product assembly process is as follows: the method comprises the steps of box body trial assembly, sealing ring assembly, screw locking, self-inspection, product inspection, packaging and warehousing.
S5.4: and finishing the assembly, inspection and warehousing of finished products.
As shown in fig. 2-4, in the present embodiment, the electronic chassis includes a top cover, a top cover assembly, a motherboard assembly, a cover-rear case, a module case, and a rear case assembly, wherein the top cover assembly, the motherboard assembly, and the module case include a plurality of parts, and since there are many parts, if it is difficult to perform simulation calculation according to the original model, the parameterized dimensional calculation model established in step S1 is a simplified chassis model based on the original model of the electronic chassis. Specifically, the simplification basis is to simplify according to the layout of the chassis during operation: (1) Simplifying the connector between the upper cover assembly and the motherboard assembly into a cuboid to replace the heat conduction effect of the connector; (2) The gasket between the cover-rear box body and the rear box body assembly is simplified to the rear box body assembly, the gasket is small in size, and meshes are not easy to divide; (3) The locking strip is simplified into a working state, main heat is transferred to other parts of the case through the locking strip due to poor heat conducting performance of the motherboard assembly under the working state of the case, the locking strip is formed by three sections of trapezoidal blocks with inclination angles in a mutual contact mode, when the case works, the head section and the tail section of the locking strip are deviated out of the original positions under the action of the pre-tightening force of the threads, and the deviated parts are in contact with the guide grooves of the rear case assembly.
The module box sets up to 8, and each module box is inside to be packaged with the components and parts that differ in quantity, and each components and parts size specification is all different simultaneously. If the heat source models are all established according to the layout of the components, the number of established heat source blocks is too large, the grid division quality is not good, and the solving precision is not high. Considering that only the heat dissipation performance of the case body needs to be evaluated in the design process of the electronic case, the heat sources are uniformly simplified into a cuboid, and due to the concentration effect of the heat sources, the cuboid is located in the middle of the module box and has the size of 30 × 1.5mm 3 。
Through the simplification of the original model of the electronic case, the number of the divided grids is greatly reduced, the grid quality is improved, the simulation calculation time is reduced, and the accuracy of the calculation result is ensured.
And importing the simplified case model and parameterized data into a design nModelr model processing module through SolidWorks and ANSYS workbench interfaces, setting a case working area, and specifically, constructing a rectangular area with the size being 1.2 times of the size of the case around the case. The motherboard assembly and the upper cover assembly adopt PCB plates, the thicknesses of the motherboard assembly and the upper cover assembly are respectively 2.5mm and 3mm, material parameters are set, as shown in tables 1-3, the air heat conductivity coefficient is 0.0261 w/(m.k), and the ambient temperature is 20 ℃.
TABLE 1 materials parameters for various components of the chassis
| Name of component | Name of Material | Number of | Thermal conductivity (w/(m.k)) | |
| Upper cover | |
1 | 167 | |
| Upper cover | PCB board | 1 | 48.9 | |
| Lid-rear box | Aluminum alloy 2A12 | 2 | 167 | |
| Rear box body assembly | |
1 | 167 | |
| Motherboard | PCB board | 1 | 48.9 | |
| Module box | Aluminum alloy 2A12 | 8 | 167 |
TABLE 2 thermal conductivity along the planar extension of PCB
TABLE 3 Chassis Domains Material parameters
| Properties | Numerical value | Unit of |
| Density of | 1.1614 | (kg m) -3 |
| Isotropic coefficient of thermal conductivity | 0.026 | (Wm) -1 C -1 |
| Specific heat capacity | 1007 | (Jkg) -1 C -1 |
| Isotropic |
1 |
Considering that the electronic chassis has more components and a complex structure, regular tetrahedral meshes are adopted for mesh division. When the grids are divided, too dense grids can cause too long calculation time, too sparse grids can cause inaccurate calculation results, considering that the heat conductivity coefficient of a working area-air area of the case is small and is 0.0261 w/(m · k), the occupied space is relatively large and is 1.2 times of the size of the case, the physical area of the case plays a main heat dissipation role, in order to obtain a more accurate result, specifically, the size of the working area-air area grid is set to be 8mm, the size of the physical area grid of the case is set to be 4mm, the simulation result is shown in fig. 5, the number of nodes of the whole electronic case is 310523, and the number of units is 168542.
The electronic case works in the atmosphere, the ambient temperature is 20 ℃, the heat source power is set to be 20W, and the boundary temperature of the working area of the electronic case is set to be 20 ℃; the face-to-face radiation temperature was set at 20 ℃ and the emission coefficient was set at 0.85. And (3) obtaining a heat source temperature cloud picture in fig. 6 (a), an outer box body temperature cloud picture in fig. 6 (b), a module box cover plate upper cover component temperature cloud picture in fig. 6 (c), a rear box body component temperature cloud picture in fig. 6 (d), a YZ plane section temperature cloud picture in fig. 6 (e) and a XZ plane section temperature cloud picture in fig. 6 (f) through calculation of a solver.
The reliability of the simulation result is analyzed by taking the temperature field distribution and the highest temperature as judgment basis, the highest rated temperature of the heat source is 85 ℃, and the highest temperature of the electronic case is about 65.4 ℃ and the lowest temperature of the electronic case is about 58.3 ℃ from fig. 6 (b), which shows that the aluminum alloy 2A12 has good heat-conducting property, light weight and is suitable for being used as a heat-radiating material, and the number of heat-radiating grooves formed on the two sides of the case is moderate.
In this embodiment, in order to facilitate grid division, calculation solution, and obtaining a more accurate simulation result, a module box simulation model is established in ANSYS workbench, as shown in fig. 7; specifically, the pins of the module box are simplified into a cuboid as shown in fig. 8 (a), the rear box assembly is simplified into the guide rails as shown in fig. 8 (b), the motherboard assembly is simplified into the slots, and the positioning holes remain unchanged as shown in fig. 8 (c). Because the contact condition of the slot and the guide rail is complex in simulation, the overall appearance and the size of the plug board model are kept unchanged in order to restore the real contact condition as much as possible; in order to simulate convergence as much as possible, chamfers are added at the contact positions of the slot and the guide rail, and chamfers are added at the root parts of the pins. The key of the module box plug simplified model simulation lies in metal pins at two ends of a plug of a slot, and the pins play a role in guiding the whole insertion process and are also the positions where the maximum deformation occurs.
In this embodiment, the module box, the guide rail and the slot are made of aluminum alloy 2a12, and the material data thereof is shown in table 4. The module box is inserted and pulled at normal temperature, and the influence of temperature on the elastic model and the Poisson ratio of the material is not considered. The cartridge material parameter settings are shown in table 5.
TABLE 4 mechanical Properties of aluminum alloys
TABLE 5 Module Box Material parameter settings
| Properties | Numerical value | Unit of |
| Density of | 2770 | (kg m) -3 |
| Coefficient of thermal expansion | 2.3E-05 | C -1 |
| Zero thermal strain reference temperature | 22 | ℃ |
| Young's modulus | 71000 | MPa |
| Poisson ratio | 0.33 | |
| Bulk modulus | 6.9608E+10 | Pa |
| Shear modulus | 2.6692E+10 | Pa |
| Ratio of | 1 | |
| |
0 | Pa |
| Tensile yield strength | 280 | MPa |
| Compressive yield strength | 280 | MPa |
| Ultimate tensile strength | 310 | MPa |
| Ultimate |
0 | MPa |
In this embodiment, there are two positions in the module box plug model that contact, and it is the contact of module box main cartridge body with the guide rail inboard respectively to and the module box bottom contact pin and the contact between locating pin and the locating hole on slot and the slot, set up two parts frictional force size to 0.3, contact normal rigidity sets up to 1.
The grid division is too dense, the solving time is too long, the product is not beneficial to rapid research and development, the grid division is too sparse, the result is not accurate enough, the influence on the plugging and unplugging force is large mainly in the contact areas of the module box, the guide rails and the slots, and the contact areas can generate resistance or extrusion force on the plugging and unplugging of the module box. Therefore, the contact area is divided independently by adopting thinner grids, specifically, the size of the thinner grids is 1mm, and the non-contact area adopts the default grid size of the system, so that the reliability of the result can be improved, the convergence process is faster, and the efficiency is improved. By solving, the result is shown in FIG. 9, the number of grid cells of the cartridge is 131190, and the number of grid nodes is 252818. The average quality value of the grid unit is 0.63508, and the quality is better. The grid mass ranges from 0 to 1, and the higher the value, the better the mass.
Because the module box moves in a direction perpendicular to the plugging direction and rotates around the plugging axis, the rotation angle of the module box around the plugging axis is set to be 0.2 degrees, so that the actual plugging process is simulated more truly, and two symmetrical rectangular planes are selected as plugging displacement applying positions on the upper end face of the module box. The insertion and extraction force of the chassis module box is a quasi-static process, and in order to make convergence faster and solution time shorter, a static analysis module is used for numerical simulation. Static analysis has no notion of time, each time point is in static equilibrium, so the displacement steps are: insertion 10mm → stay → withdrawal 10mm.
After the Solution is completed according to the set parameters, the Solution is used for post-processing, and the results are shown as an equivalent strain cloud chart in fig. 10 (a), a partial enlarged view of the equivalent strain cloud chart in fig. 10 (b), an equivalent stress cloud chart in fig. 10 (c) and an enlarged view of the equivalent stress cloud chart in fig. 10 (d), and the equivalent stress and the equivalent strain in the process of inserting and pulling the module box can be observed from the diagrams.
From the equivalent strain cloud chart, when the module box has an offset angle of 0.2 degrees, the maximum equivalent strain value is about 0.0035mm/mm, and the deformation amount is not large; the maximum equivalent stress value is about 246.8Mpa, the 2A12 aluminum alloy yield strength is 280Mpa, and the maximum equivalent stress value meets the requirement, which is shown by the aluminum alloy performance data table in Table 4. The maximum deformation and stress area can be obtained through the equivalent strain and equivalent stress local graph and is positioned at the positioning pin of the module box and the positioning hole of the slot, which shows that the part is a frequent wear area when the module box is plugged and unplugged. In the actual insertion and extraction process, the cartridge should be inserted and extracted as much as possible without an offset angle or by using a material having a high yield strength to prevent the plastic deformation of the portion.
According to the manufacturing method of the spaceflight electronic chassis, the surface characteristics and the size set of the model are obtained by establishing the dimensional calculation model, the size chain is searched by combining the search algorithm, and the size of the dimensional tolerance of the closed ring is automatically calculated, so that a large amount of repeated manual work for calculating the dimensional tolerance is avoided, and the calculation efficiency is improved; the ACT plug-in is formed by establishing a case thermal analysis and module box plugging force analysis parameterized simulation flow, in the design process of the aerospace electronic case, under the condition that data are continuously changed, all parameters are required to be changed again on a parameterized interface without modeling and simulation again, the parameterized plug-in is convenient to operate and use, and the simulation efficiency is improved.
According to the manufacturing method of the space electronic case, the size chain where the closed ring is located is searched and obtained by adopting the size chain loop, and compared with a traditional manual size chain calculation method which is large in calculation workload and low in calculation efficiency particularly when the marked size and the coordinate axis have a certain angle, the calculation workload is small and the efficiency is high; calculating the packaging layout of the electronic device and the plugging and unplugging angles and the offset of the module box by establishing a dimension parameterization calculation model and calculating the dimensional tolerance of the chassis and analyzing the parameterized simulation process ACT plug-in unit according to the established thermal analysis of the chassis and the plugging and unplugging force of the module box; and the dimensional tolerance of the electronic case is obtained, the structural design and reliability analysis in the design process of the electronic case are combined, the operation is easy, and the design efficiency of the electronic case is improved.
It will be understood by those skilled in the art that all or part of the flow of the method implementing the above embodiments may be stored in a computer-readable storage medium, where the program may be executed by a computer program to instruct associated hardware. The computer readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory.
While the invention has been described with reference to specific preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
Claims (2)
1. A manufacturing method of an aerospace electronics chassis is characterized by comprising the following steps:
s1: establishing a dimensional parameterization calculation model, and preliminarily calculating the dimensional tolerance of the case; in the S1, the parameterization calculation refers to that dimension tolerance is marked in three-dimensional software through man-machine interaction, model surface characteristics and dimension sets are obtained, a dimension chain is searched, and the dimension tolerance of the closed ring is automatically calculated;
the step S1 comprises the following steps:
s1.1: marking the dimensional tolerance of the assembly body or the part; in the S1.1, the content of the dimension tolerance marking is basic dimension, upper and lower deviation and dimension annotation, and the marking mode of the dimension tolerance marking adopts surface-to-surface marking;
s1.2: obtaining size information marked by size tolerance and establishing a size information set;
s1.3: determining a closed ring, and selecting the end face of the closed ring;
s1.4: acquiring a size chain where the closed ring is located according to the size information set and the end face of the closed ring; in the step S1.4, a size chain in which the closed ring is located is obtained by adopting size chain loop search, wherein the size chain loop search refers to a process of returning from one end face of the closed ring to the other end face of the closed ring through a group of ordered component rings;
s1.5: calculating the size of the closed loop by adopting a loop method according to the acquired size chain; in S1.5, the loop method is to determine the increase or decrease of the component ring according to the difference between the closed ring direction and the component ring direction;
s2: carrying out cabinet thermal analysis and module box insertion and extraction force analysis parameterized simulation;
the step in S2 comprises:
s2.1: parameterizing the mould material data;
s2.2: parameterizing model size data;
s2.3: parameterizing initial solution parameters of the model;
s2.4: parameterizing the size of the model mesh division;
s3: calculating the packaging layout of the electronic device and the plugging angle and the offset of the module box;
the step in S3 comprises:
s3.1: loading a parameterized plug-in; in the S3.1, the parameterized plug-in is an ACT plug-in of a case thermal analysis and module box insertion and extraction force analysis parameterized simulation process established in the S2;
s3.2: inputting data parameters on a parameterized interface for solving;
s3.3: judging whether the solving result meets the requirement, if so, performing S4, otherwise, modifying the data parameters and performing S3.2;
s4: calculating to obtain the size tolerance of the chassis;
s5: and manufacturing the electronic chassis according to the dimensional tolerance.
2. The manufacturing method according to claim 1, wherein the step in S4 includes:
s4.1: updating the design size of the case according to the solving result of the S3;
s4.2: and recalculating dimensional tolerances of all parts of the chassis.
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