A method for molding an aluminum alloy child safety seat frame

Abstract

This invention relates to a molding method for an aluminum alloy child safety seat frame, belonging to the automotive field, and solves the problem that existing aluminum alloys cannot be used to mold child safety seat frames. The method includes: preparing aluminum alloy powder for molding the child safety seat frame; designing the dimensions and shape of the child safety seat frame, creating a model using 3D modeling software; converting the child safety seat frame model file to STL format, defining the printing direction, determining the number of printing layers and spacing using slicing software, and obtaining a slicing file; importing the slicing file into a 3D printer, inputting printing parameters, and printing to obtain a first child safety seat frame; subjecting the first child safety seat frame to hot isostatic pressing or conventional heat treatment to obtain a second child safety seat frame; and sandblasting the second child safety seat frame to obtain the final child safety seat frame. This invention can integrally mold a child safety seat frame, meeting usage requirements.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to a method for molding an aluminum alloy child safety seat frame. Background Technology

[0002] Child safety seat materials can be divided into two categories: the main support material and the cushioning material that provides protection. The main support material is primarily made of steel or plastic. Steel offers higher strength and better toughness, but it is relatively heavy and difficult to carry. Furthermore, ISOFIX connectors (an international standard for child car seat installation) have weight limits; extensive use of steel frames would make the car seat too heavy, inconvenient to carry, and, more importantly, increase the seat's inertia, increasing the risk of the child being ejected in a collision. Therefore, car seats with a pure steel frame are rare. Plastic car seats have low density but relatively low strength, making them easily deformed in a collision, threatening the child's life. To meet the strength requirements of the support structure and the weight-bearing capacity of the connectors, high-end child safety seats currently often use a plastic + steel frame structure.

[0003] Steel child safety seat frames, due to their complex shapes and high strength, are generally formed using cold stamping or hot stamping. The biggest drawback of these two processes is the need to design specific molds based on the shape of the components, resulting in complex processing, high mold and equipment maintenance costs, long production cycles, and low material utilization, typically not exceeding 75%, leading to significant raw material waste. Aluminum alloys have a lower density than steel, approximately one-third that of steel. Furthermore, compared to steel, aluminum alloys have superior corrosion resistance, require no painting, are more environmentally friendly, and are easily recyclable with low reprocessing costs, making them an energy-saving and environmentally friendly material. However, traditional high-strength aluminum alloys suffer from insufficient toughness, poor formability, and poor weldability. Since the shapes of child safety seat frames are complex, high-strength aluminum alloys are difficult to form in a single operation, thus preventing their application in child safety seats.

[0004] 3D printing technology uses powder and filament as raw materials to create three-dimensional models and slice them to form components layer by layer. It is the best way to form complex shapes. However, traditional grades of aluminum alloys are prone to printing cracks during the printing process, which cannot meet the requirements of 3D printing. Existing aluminum alloy products obtained by 3D printing by adjusting the composition of aluminum alloys cannot meet the performance requirements of child safety seat frames. Summary of the Invention

[0005] Based on the above analysis, the embodiments of the present invention aim to provide a molding method for an aluminum alloy child safety seat to solve at least one of the following technical problems: 1. When steel is used as the frame of a child seat, the high density and low specific strength of steel result in an excessively heavy frame with high inertia, increasing the risk of the child being thrown out during a collision; 2. When plastic is used as the frame of a child seat, the low density and relatively low strength of plastic make it easily deformed during a collision, threatening the child's life; 3. Existing high-end child safety seats often use a plastic + steel frame structure. The steel frame is generally formed by cold stamping or hot stamping, requiring the design of specific molds according to the shape of the frame, resulting in complex processing technology and a long production cycle; 4. Existing grades of aluminum alloys used for 3D printing do not meet the strength, toughness, and formability requirements for child safety seat frames and cannot be used to manufacture child safety seats.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for molding an aluminum alloy child safety seat frame, comprising the following steps:

[0008] Step 1: Prepare aluminum alloy powder for molding child safety seat frames. The composition ratio of the aluminum alloy powder, by mass percentage, is: Mg: 3.0-5.5%, Zr: 0.15-1.25%, Mn: 0.51-2.0%, Si: 0.1-2.5%, Sc: 0.15-0.75%, Ti≤0.5%, Fe≤0.4%, Er≤0.5%, Y≤0.5%, with the remainder being Al and non-removable impurity elements.

[0009] Step 2: Design the dimensions and shape of the child safety seat frame, and create a model using 3D modeling software to obtain the child safety seat frame model;

[0010] Step 3: Convert the child safety seat frame model file to STL format, define the printing direction, determine the number of printing layers and spacing using slicing software, and obtain the slice file;

[0011] Step 4: Import the sliced ​​file into the 3D printer, input the printing parameters, and 3D print to obtain the first child safety seat frame;

[0012] Step 5: Perform hot isostatic pressing or ordinary heat treatment on the first child safety seat frame to obtain the second child safety seat frame;

[0013] Step 6: Perform sandblasting on the second child safety seat frame 1 to 3 times to obtain the child safety seat frame.

[0014] Further, step 1 includes:

[0015] S11: Weigh a certain amount of pure metal ingots and / or alloy ingots, Si powder, and ZrH2 powder according to the aluminum alloy composition ratio;

[0016] S12: Obtain pre-alloyed ingots by vacuum melting pure metal ingots and alloy ingots;

[0017] S13: Obtain the first pre-alloy powder by atomizing the pre-alloyed ingot;

[0018] S14: Powder mixing: The first pre-alloyed powder is mixed with Si powder and ZrH2 powder using a three-dimensional powder mixer or ball mill to obtain the second pre-alloyed powder.

[0019] S15: The second pre-alloyed powder is sieved through a sieve to obtain a third pre-alloyed powder that meets the size and shape requirements;

[0020] S16: Vacuum drying is performed on the third pre-alloyed powder obtained by sieving that meets the size and shape requirements to obtain aluminum alloy powder.

[0021] Furthermore, in step S11, the particle size of the Si powder and ZrH2 powder is 2–5 μm.

[0022] Further, in step S14, the powder mixing process is as follows: adding zirconia balls as a powder mixing medium, and mixing the first pre-alloyed powder with Si powder and ZrH2 powder through a three-dimensional powder mixer or ball mill;

[0023] The rotation speed of the three-dimensional powder mixer or ball mill is 10-20 r / min, the mixing time is 2-10 h, and the mass ratio of zirconium oxide in the zirconium oxide balls is 15-25%.

[0024] Further, step 2 includes:

[0025] S21: Design the dimensions and shape of the target child safety seat frame;

[0026] S22: Based on the size and shape of the target child safety seat frame, use the sketching tool of the modeling software to draw the basic shape and size of the child safety seat frame on a plane;

[0027] S23: Using the feature tools of modeling software, the sketch is converted into a three-dimensional solid to obtain the first child safety seat frame model;

[0028] S24: Use finite element simulation software to simulate and analyze the stress field, strain field, and mass of the first child safety seat frame model;

[0029] S25: Based on the simulation analysis results, determine whether the model analysis results meet the stopping iteration condition. If they do, determine the child safety seat frame model. If they do not meet, perform structural optimization on the first child safety seat frame model to obtain the second child safety seat frame model.

[0030] S26: Simulate and analyze the stress field, strain field, and mass of the second child safety seat frame model. Based on the simulation analysis results, determine whether the model analysis results meet the stopping iteration condition. If they do, the second child safety seat frame model is determined to be the final child safety seat frame model. If not, perform structural optimization on the second child safety seat frame model and repeat the simulation analysis until the Nth child safety seat frame model obtained after N iterations meets the stopping iteration condition, which is then the final child safety seat frame model.

[0031] Further, in step S25, the stopping iteration condition is: simultaneously satisfying the ratio of the equivalent stress of the Nth child safety seat frame model to the stress of the target child safety seat frame ≥ 1, and the mass ratio of the Nth child safety seat frame model to the target child safety seat frame ≤ 0.4.

[0032] Furthermore, in step 4, the 3D printing is selective laser melting, and the substrate of the selective laser melting equipment is preheated at a temperature of 50 to 320°C.

[0033] Furthermore, the selective laser melting parameters are: scanning power of 200-400W, scanning speed of 400-1200mm / s, powder thickness of 0.03-0.1mm, and scanning spacing of 0.09-0.2mm.

[0034] Furthermore, the aging temperature of the conventional heat treatment is 360-520℃, and the time is 2-6 hours; the temperature of the hot isostatic pressing is 360-520℃, the pressure is 60-150 MPa, and the time is 2-6 hours.

[0035] The present invention also provides an aluminum alloy child safety seat frame formed according to the above-described forming method.

[0036] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0037] 1. This invention controls the component ratio of the aluminum alloy child safety seat frame and uses 3D printing technology to integrally form the child safety seat frame, avoiding cracking of the aluminum alloy during the stamping process; at the same time, since no mold is required, the process is simple, and in addition to reducing the weight through material, further weight reduction can be achieved through structural design.

[0038] 2. This invention uses 3D printing technology to integrally form the child safety seat frame, which is simple and requires less factory space. In addition, compared with steel child safety seat frames, the aluminum alloy child safety seat frame of this invention can be used without painting, which is more environmentally friendly, easy to recycle, and has low reprocessing costs. Moreover, the entire molding process is basically carried out in a closed environment, so the working environment is more "green" and has no pollution to the environment.

[0039] 3. This invention uses controlled aluminum alloy composition and 3D printing technology to integrally mold a child safety seat frame, resulting in a child safety seat frame with a tensile strength ≥450MPa, yield strength ≥400MPa, elongation ≥13%, density ≥99.5%, and specific strength ≥0.16N·m / kg. For reference, a child safety seat frame of the same shape and size made from 780MPa ultra-high strength steel typically has a specific strength of 0.1N·m / kg. The aluminum alloy child safety seat frame of this invention can increase the specific strength by at least 60% and achieve a weight reduction of over 60%, meeting the requirements for child safety seat frames.

[0040] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0041] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0042] Figure 1 This is a schematic diagram of the aluminum alloy child safety seat frame according to Embodiment 1 of the present invention;

[0043] Figure 2 This is a microstructure diagram of the aluminum alloy child safety seat frame of Embodiment 1 of the present invention;

[0044] Figure 3 This is a microstructure diagram of the aluminum alloy child safety seat frame, which is Comparative Example 1 of the present invention. Detailed Implementation

[0045] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0046] This invention provides a method for molding an aluminum alloy child safety seat frame, comprising the following steps:

[0047] Step 1: Prepare aluminum alloy powder for molding child safety seat frames. The composition ratio of the aluminum alloy powder, by mass percentage, is: Mg: 3.0-5.5%, Zr: 0.15-1.25%, Mn: 0.51-2.0%, Si: 0.1-2.5%, Sc: 0.15-0.75%, Ti≤0.5%, Fe≤0.4%, Er≤0.5%, Y≤0.5%, with the remainder being Al and non-removable impurity elements.

[0048] Step 2: Design the dimensions and shape of the child safety seat frame, and create a model using 3D modeling software to obtain the child safety seat frame model;

[0049] Step 3: Convert the child safety seat frame model file to STL format, define the printing direction, determine the number of printing layers and spacing using slicing software, and obtain the slice file;

[0050] Step 4: Import the sliced ​​file into the 3D printer, input the printing parameters, and 3D print to obtain the first child safety seat frame;

[0051] Step 5: Perform hot isostatic pressing or ordinary heat treatment on the first child safety seat frame to obtain the second child safety seat frame;

[0052] Step 6: Perform sandblasting on the second child safety seat frame 1 to 3 times to obtain the child safety seat frame.

[0053] High-end child safety seats often use a plastic + steel frame structure, such as the German Osann Starship safety seat. Aluminum alloy has a lower density than steel, about one-third that of steel; furthermore, aluminum alloy has superior corrosion resistance compared to steel, requiring no painting and is more environmentally friendly. Aluminum alloy is also easily recyclable, with low reprocessing costs, making it an energy-saving and environmentally friendly material. However, traditional aluminum alloys lack sufficient strength and toughness, and due to the complex shape of child safety seat frames, medium- and high-strength aluminum alloys are difficult to mold in a single piece. Therefore, aluminum alloys have not been widely used in child safety seats. To address the aforementioned issues, this invention utilizes controlled aluminum alloy composition and 3D printing technology to integrally mold a child safety seat frame. The resulting child safety seat frame exhibits a tensile strength ≥450MPa, yield strength ≥400MPa, elongation ≥13%, density ≥99.5%, and specific strength ≥0.16N·m / kg. Taking 780MPa ultra-high-strength steel as an example, its specific strength is typically 0.1N·m / kg. This demonstrates that the aluminum alloy used in this invention for molding the child safety seat frame can increase the specific strength by 60% and achieve a weight reduction of over 60%. The aluminum alloy child safety seat frame of this invention meets the requirements for child safety seat frames, possesses a certain degree of toughness, and can prevent secondary injuries to children caused by frame breakage during car collisions.

[0054] Specifically, in step 1, the preparation of aluminum alloy powder for the child safety seat frame includes the following steps:

[0055] S11: Weigh a certain amount of pure metal ingots and / or alloy ingots, Si powder, and ZrH2 powder according to the aluminum alloy composition ratio;

[0056] S12: Obtain pre-alloyed ingots by vacuum melting pure metal ingots and alloy ingots;

[0057] S13: Obtain the first pre-alloy powder by atomizing the pre-alloyed ingot;

[0058] S14: Powder mixing: The first pre-alloyed powder is mixed with Si powder and ZrH2 powder using a three-dimensional powder mixer or ball mill to obtain the second pre-alloyed powder.

[0059] S15: The second pre-alloyed powder is sieved through a sieve to obtain a third pre-alloyed powder that meets the size and shape requirements;

[0060] S16: Vacuum drying is performed on the third pre-alloyed powder obtained by sieving that meets the size and shape requirements to obtain aluminum alloy powder.

[0061] Specifically, in step S11, the pure metal ingots include Al ingots, Mg ingots, Mn ingots, Zr ingots, Ti ingots, Er ingots, Sc ingots, and Y ingots; the alloy ingots include Al-Mg master alloys and Al-Sc master alloys for later use. The particle size of the Si powder is 2-5 μm, and the particle size of the ZrH2 powder is 2-5 μm.

[0062] The rationale for limiting the component proportions of the aluminum alloy child safety seat in this invention will be explained below, where only % is used to represent the mass percentage of the components:

[0063] Mg: Improves the corrosion resistance of alloys and reduces the density of aluminum alloys; solid solution strengthening can improve the strength and yield strength of aluminum alloys; studies have shown that for every 1% increase in the mass fraction of Mg in the aluminum alloy matrix, the alloy strength increases by 30-35 MPa, and the alloy density decreases by about 0.5%. Excessive Mg content can easily lead to the precipitation of β phase at grain boundaries and the formation of "yellow fumes" that contaminate equipment; therefore, the Mg content should be controlled between 3.0% and 5.5%.

[0064] Zr: A modifying element that promotes the formation of equiaxed crystals and reduces the tendency of aluminum alloys to crack during printing. When the content is below 0.15%, it cannot modify the printability of aluminum alloys. When it exceeds 1.25%, it has limited effect on improving the printability of aluminum alloys and significantly increases the density of aluminum alloys. Therefore, the Zr content should be controlled between 0.15% and 1.25%.

[0065] Mn: Improves the heat resistance and strength of aluminum alloys. For every 0.1% increase in Mn content, the strength of the alloy increases by 5 to 7 MPa. When the manganese content is too high, it will form coarse, hard and brittle Al6Mn phase, which will damage the toughness of the aluminum alloy. Therefore, the Mn content should be controlled between 0.51% and 2.0%.

[0066] Si can act as a nucleation point to promote the formation of equiaxed grains and reduce the tendency of aluminum alloys to crack during printing, thereby reducing the addition of Zr and Sc. In addition, it can disperse with Mg to precipitate Mg2Si to improve the strength of aluminum alloys. If the content is too low, it will not improve its printing performance. If the content is too high, Si will precipitate along the grain boundaries in a network, affecting the toughness of the material. Therefore, the Si content should be controlled between 0.1% and 2.5%.

[0067] Sc: A modifier element that reduces the tendency of aluminum alloys to crack during printing, thus giving the aluminum alloys good formability. However, when the content exceeds 0.75%, the improvement effect on the aluminum alloy becomes negligible and increases material costs; therefore, the Sc content should be controlled below 0.75%.

[0068] Ti: Deoxidizing element, used to control the oxygen content of aluminum alloys. Excessive content can easily lead to the precipitation of brittle phases. Its content is usually controlled below 0.5%.

[0069] Fe: Increases the recrystallization temperature and strength of aluminum alloys, but excessive content will impair the corrosion resistance and mechanical properties of the alloy. It is usually controlled below 0.4%.

[0070] Er and Y: Modifying elements that reduce the tendency of aluminum alloys to crack during printing, thus giving the aluminum alloys good formability. However, the effect of improving the formability of aluminum alloys is not obvious when the content exceeds 0.5%; therefore, the content of Er and Y is controlled at ≤0.5%.

[0071] Preferably, in step S11, the aluminum alloy composition ratio, expressed as a mass percentage, is: Mg: 3.5-5.0%, Zr: 0.45-1.20%, Mn: 0.74-1.2%, Si: 0.1-1.5%, Sc: 0.30-0.72%, Ti≤0.5%, Fe≤0.4%, Er≤0.5%, Y≤0.5%, with the remainder being Al and non-removable impurity elements.

[0072] Specifically, in step S12, the vacuum melting includes the following steps:

[0073] S121: Place the weighed Al ingots into the crucible of the vacuum intermediate frequency induction furnace, evacuate the furnace, and when the vacuum degree is less than 1*10... - 2 When Pa, heating begins and argon gas is introduced to create a positive pressure environment inside the furnace;

[0074] S122: Other pure metal ingots and / or alloy ingots are added in order of their melting points from high to low. After they are completely melted, they are degassed, stirred, and poured to obtain pre-alloyed ingots.

[0075] Specifically, in step S121, the Al ingot is heated at a heating rate of 5 to 20°C / s. When the temperature inside the furnace reaches 700 to 850°C, the heating is stopped, and the holding time is 0.5 to 2 hours. Within this temperature range, the Al ingot is completely melted and in a liquid state.

[0076] Specifically, in step S122, other pure metal ingots and alloy ingots are added in order of their melting points from high to low. After the alloy ingots are completely melted, hexachloroethane is added first to degas the mixture. Then, the mixture is stirred electromagnetically at a speed of 200-500 r / min to ensure that all elements are mixed evenly. After being kept at a constant temperature and cooled for 30-40 minutes, the casting begins. The casting temperature is 700-850℃ and the alloy flow rate is 5-10 kg / min.

[0077] Specifically, in step S13, the pre-alloyed ingot is atomized to obtain the first pre-alloyed powder; the atomization can be achieved by nitrogen atomization, argon atomization, plasma rotation atomization, etc.; preferably, the atomization is completed by argon atomization, with an atomization pressure of 1.5 to 4.5 MPa and an atomization temperature of 700 to 850°C.

[0078] Specifically, in step S14, the first pre-alloyed powder is mixed with Si powder and ZrH2 powder using a three-dimensional powder mixer or ball mill to obtain the second pre-alloyed powder. The rotation speed of the three-dimensional powder mixer or ball mill is 10-20 r / min. During the mixing process, zirconia balls with a mass ratio of 15-25% are added as a mixing medium to improve the mixing efficiency and uniformity. The mixing time is 2-10 hours. After mixing, the zirconia balls are removed. This step introduces high-melting-point particles Si and Zr as nucleation sites to promote equiaxed grain nucleation, thereby improving the formability and strength of the aluminum alloy.

[0079] Specifically, in step S15, the second pre-alloyed powder is sieved through a 100-1000 mesh sieve to obtain a third pre-alloyed powder that meets the size and shape requirements. The powder size is 3-105 μm and the powder shape is nearly spherical, which can ensure the flowability of the powder. Preferably, the size of the third pre-alloyed powder is 3-53 μm.

[0080] Specifically, in step S16, the third pre-alloy powder that meets the size and shape requirements obtained by sieving is vacuum dried in a vacuum oven at a temperature of 100-140°C for 2-8 hours to obtain aluminum alloy powder. If the drying temperature is too high or the drying time is too long, the powder surface will be severely oxidized. If the drying temperature is too low or the time is too short, the moisture in the powder cannot be completely removed, which will affect the sintering activity of the powder.

[0081] Specifically, in step 2, the dimensions and shape of the child safety seat frame are designed, and a 3D modeling software is used to create the model, which includes the following steps:

[0082] S21: Design the dimensions and shape of the target child safety seat frame;

[0083] S22: Based on the size and shape of the target child safety seat frame, use the sketching tool of the modeling software to draw the basic shape and size of the child safety seat frame on a plane;

[0084] S23: Using the feature tools of modeling software, the sketch is converted into a three-dimensional solid to obtain the first child safety seat frame model;

[0085] S24: Use finite element simulation software to simulate and analyze the stress field, strain field, and mass of the first child safety seat frame model;

[0086] S25: Based on the simulation analysis results, determine whether the model analysis results meet the stopping iteration condition. If they do, determine the child safety seat frame model. If they do not meet, perform structural optimization on the first child safety seat frame model to obtain the second child safety seat frame model.

[0087] S26: Simulate and analyze the stress field, strain field, and mass of the second child safety seat frame model. Based on the simulation analysis results, determine whether the model analysis results meet the stopping iteration condition. If they do, the second child safety seat frame model is determined to be the final child safety seat frame model. If not, perform structural optimization on the second child safety seat frame model and repeat the simulation analysis until the Nth child safety seat frame model obtained after N iterations meets the stopping iteration condition, which is then the final child safety seat frame model.

[0088] It should be noted that the stopping iteration condition is: the ratio of the equivalent stress of the Nth child safety seat frame model to the stress of the target child safety seat frame is ≥1, and the mass ratio of the Nth child safety seat frame model to the target child safety seat frame is ≤0.4.

[0089] Specifically, in step 3, the child safety seat frame model file is converted to STL format, and the printing direction is defined using slicing software; the number of printing layers and spacing are determined based on the dimensions of the child safety seat frame model to obtain the slice file; typically, the height direction of the child safety seat frame model is the printing direction.

[0090] Specifically, in step 4, the sliced ​​file is imported into the 3D printer, printing parameters are entered, and printing is performed to obtain the first child safety seat frame. Before use, the material hopper must be checked to avoid foreign objects in the printing area; the filter element must be checked to avoid clogging. The aluminum alloy powder prepared in step 1 is shaped into the first child safety seat frame using selective laser melting (SLM). The parameters are: scanning power of 300-350W, scanning speed of 200-800mm / s, powder thickness of 0.01-0.05mm, and scanning spacing of 0.05-0.1mm. The substrate of the selective laser melting equipment is preheated at a temperature of 25-250℃, mainly to promote equiaxed crystal nuclei in the aluminum alloy and reduce the tendency of aluminum alloy to crack during printing. After removing the substrate used for 3D printing, the surface aluminum alloy powder is removed by brushing, and excess aluminum alloy powder is swept into the powder hopper. The excess aluminum alloy powder is sieved and dried, and can be recycled after meeting the usage requirements of this invention.

[0091] Specifically, in step 5, the first child safety seat frame is subjected to hot isostatic pressing (HIP) or conventional heat treatment to obtain the second child safety seat frame. The conventional heat treatment aging temperature is 360-520℃ for 2-6 hours; the HIP temperature is 360-520℃, the pressure is 60-150 MPa, and the time is 2-6 hours. Preferably, the HIP temperature is 360-420℃ and the pressure is 70-100 MPa. This step promotes the precipitation of dispersed phases Al3Sc, Al3(Sc,Zr), Al3Zr, and Mg2Si in the aluminum alloy microstructure, thereby improving the material's strength.

[0092] Specifically, in step 6, the second child safety seat frame is sandblasted 1 to 3 times to obtain a smooth aluminum alloy child safety seat frame.

[0093] The aluminum alloy child safety seat frame prepared by the method of this invention is free of cracks, has fine grains, excellent strength-plasticity matching performance, and high specific strength; its tensile strength is ≥450MPa, yield strength is ≥400MPa, elongation is ≥13%, density is ≥99.5%, and specific strength is ≥0.16N·m / kg, which meets the requirements for use of child safety seat frames.

[0094] Example 1

[0095] A method for molding an aluminum alloy child safety seat frame includes the following steps:

[0096] Step 1: Prepare aluminum alloy powder for child safety seat frames;

[0097] S11: Weigh a certain amount of pure metal ingots and / or alloy ingots, Si powder, and ZrH2 powder according to the aluminum alloy composition ratio;

[0098] The aluminum alloy composition, by mass percentage, is as follows: Mg: 3.5%, Zr: 1.2%, Mn: 0.74%, Si: 1.2%, Sc: 0.30%, Fe: 0.03%, Ti: 0.02%, with the remainder being Al and non-removable impurity elements.

[0099] According to the component ratio, weigh out 10 kg of Al ingots, Mg ingots, Zr ingots, Mn ingots, Ti ingots and Al-Sc ingots with a purity of 99.9% or higher;

[0100] The Si powder has a size of 3 μm and a mass of 0.11 kg; the ZrH2 powder has a size of 3 μm and a mass of 0.11 kg.

[0101] S12: Obtain alloy ingots by vacuum melting pure metal ingots and alloy ingots;

[0102] S121: Place the weighed aluminum ingots into the crucible of the vacuum intermediate frequency induction furnace, evacuate the furnace, and when the vacuum degree is less than 1*10... - 2 When Pa, heating begins and argon gas is introduced to create a positive pressure environment inside the furnace; the heating rate is 15℃ / s, and heating is stopped after the furnace temperature reaches 700~850℃, and the furnace is held at that temperature for 1 hour.

[0103] S122: According to the melting point of the billet, other pure metal ingots and alloy ingots are added in order from high to low. After the alloy ingot is completely melted, hexachloroethane is added to degas the ingot. The mixture is stirred by electromagnetic stirring at a speed of 200 r / min to make the elements evenly mixed. After holding and settling for 30 minutes, the casting begins. The casting temperature is 750℃ and the casting alloy flow rate is 5 kg / min to obtain the pre-alloyed ingot.

[0104] S13: The pre-alloyed ingot is powdered by argon atomization at a pressure of 2.5 MPa and a temperature of 750°C to obtain the first pre-alloyed powder.

[0105] S14: The first pre-alloyed powder is mixed with Si powder and ZrH2 powder by a three-dimensional powder mixer or ball mill to obtain the second pre-alloyed powder. The speed of the three-dimensional powder mixer or ball mill is 12 r / min. During the powder mixing process, zirconia balls with a mass ratio of 20% are added as the powder mixing medium. The powder mixing time is 3 hours. After the powder mixing is completed, the zirconia balls are removed.

[0106] S15: The second pre-alloyed powder is processed through a mesh sieve to obtain a third pre-alloyed powder with a size of 3-53 μm and a near-spherical shape;

[0107] S16: Vacuum drying is performed on the near-spherical third pre-alloy powder with a size of 3-53 μm obtained by sieving to obtain aluminum alloy powder; the drying temperature is 100℃ and the drying time is 6h.

[0108] Step 2: Design the dimensions and shape of the child safety seat frame, and create a model using 3D modeling software to obtain the child safety seat frame model;

[0109] Design the size and shape of the child safety seat frame, such as Figure 1As shown, a matrix is ​​formed by hexagonal elements with a side length of 5.4 mm and a wall thickness of 0.4 mm. The matrix is ​​approximately 80 mm long, 90 mm wide, and 3 mm high. Using the sketch tool of the modeling software, the basic shape and dimensions of the child safety seat frame are drawn on a plane. Using the feature tool of the modeling software, the sketch is converted into a three-dimensional solid, resulting in the first child safety seat frame model. Finite element simulation software is used to simulate and analyze the stress field, strain field, and mass of the first child safety seat frame model. The simulation analysis shows that the ratio of the equivalent stress of the first child safety seat frame model to the stress of the target child safety seat frame is 1.05, and the mass ratio of the first child safety seat frame model to the target child safety seat frame is 0.3, satisfying the stopping iteration condition.

[0110] Step 3: Convert the child safety seat frame model file to STL format, define the height direction of the child safety seat frame as the printing direction using slicing software, and set the printing spacing to 0.1mm to obtain the sliced ​​file;

[0111] Step 4: Import the sliced ​​file into the 3D printer, input the printing parameters, and 3D print to obtain the first child safety seat frame;

[0112] Before use, check the material trough to avoid foreign objects in the printing area; check the filter element to avoid clogging.

[0113] The selective laser melting (SLM) printing parameters are as follows: scanning power of 330W, scanning speed of 800mm / s, powder thickness of 0.05mm, and scanning spacing of 0.1mm. The substrate is preheated to 50℃.

[0114] Step 5: Place the child safety seat frame in a conventional heat treatment furnace for aging heat treatment at a temperature of 420℃ for 2 hours to obtain the second child safety seat frame;

[0115] Step 6: Perform three sandblasting processes on the second child safety seat frame to obtain a smooth surface on the child safety seat frame.

[0116] This embodiment allows for the one-piece molding of a child safety seat frame that meets performance requirements. The resulting target aluminum alloy part is crack-free, and its microstructure is shown in Figure 2. The tensile strength is 455 MPa, the yield strength is 400 MPa, the elongation is 14%, and the density is 2.743 g / cm³. 3 The density is 99.9% and the specific strength is 0.165 N·m / kg. Taking a child safety seat frame of the same shape and size made of 780 MPa ultra-high strength steel as a reference, its specific strength is about 0.1 N·m / kg. The weight reduction rate of the aluminum alloy child safety seat frame in this embodiment is about 65%.

[0117] Example 2

[0118] The aluminum alloy composition of the child safety seat frame in this embodiment, by mass percentage, is as follows: Mg: 4.5%, Sc: 0.35%, Zr: 0.45%, Mn: 1.2%, Si: 0.1%, Fe: 0.03%, Ti: 0.01%, Er: 0.15%, Y: 0.15%, with the remainder being Al and non-removable impurity elements.

[0119] According to the component ratio, weigh out 25 kg of Al ingots, Mg ingots, Zr ingots, Mn ingots, Er ingots, Y ingots, Ti ingots and Al-Sc ingots with a purity of 99% or higher.

[0120] The Si powder has a particle size of 3 μm and a mass of 0.025 kg; the ZrH2 powder has a particle size of 3 μm and a mass of 0.11 kg.

[0121] The remaining steps and process parameters are the same as in Example 1.

[0122] This embodiment can integrally mold a child safety seat frame that meets performance requirements. The resulting target aluminum alloy part is crack-free, with a tensile strength of 460 MPa, a yield strength of 410 MPa, an elongation of 15.2%, and a density of 2.744 g / cm³. 3 The density is 99.5%, and the specific strength is 0.168 N·m / kg. Taking a child safety seat frame of the same shape and size made of 780 MPa ultra-high strength steel as a reference, its specific strength is about 0.1 N·m / kg. The weight reduction rate of the aluminum alloy child safety seat frame in this embodiment is about 68%.

[0123] Example 3

[0124] The composition of the aluminum alloy used in the child safety seat frame of this embodiment, by mass percentage, is as follows: Mg: 5.0%, Zr: 0.7%, Mn: 0.74%, Si: 1.5%, Sc: 0.72%, Fe: 0.02%, Ti: 0.02%, Y: 0.15%, with the remainder being Al and non-removable impurity elements.

[0125] According to the component ratio, weigh out 20 kg of Al ingots, Mg ingots, Zr ingots, Mn ingots, Ti ingots, Y ingots, and Al-Sc ingots with a purity of 99% or higher;

[0126] The Si powder has a size of 3 μm and a mass of 0.29 kg; the ZrH2 powder has a size of 3 μm and a mass of 0.14 kg.

[0127] The aluminum alloy powder preparation process, modeling process, parameters in the 3D printing process, and sandblasting treatment are the same as in Example 1. The difference is that in this example, aging heat treatment is carried out in a hot isostatic pressing furnace at a temperature of 360°C, a pressure of 100 MPa, and a time of 3 hours.

[0128] This embodiment can integrally mold a child safety seat frame that meets performance requirements. The resulting target aluminum alloy part is crack-free, with a tensile strength of 515 MPa, a yield strength of 465 MPa, an elongation of 14%, and a density of 2.713 g / cm³. 3 The density is 99.8%, and the specific strength is 0.19 N·m / kg. Taking a child safety seat frame of the same shape and size made of 780 MPa ultra-high strength steel as a reference, its specific strength is about 0.1 N·m / kg. The weight reduction rate of the aluminum alloy child safety seat frame in this embodiment is about 90%.

[0129] Example 4

[0130] The composition of the aluminum alloy used in the child safety seat frame of this embodiment, by mass percentage, is as follows: Mg: 5.0%, Zr: 0.7%, Mn: 0.74%, Si: 1.5%, Sc: 0.72%, Fe: 0.02%, Ti: 0.02%, Y: 0.15%, with the remainder being Al and non-removable impurity elements.

[0131] According to the component ratio, weigh out 20 kg of Al ingots, Mg ingots, Zr ingots, Mn ingots, Y ingots, Ti ingots and Al-Sc ingots with a purity of 99% or higher;

[0132] The Si powder has a size of 3 μm and a mass of 0.29 kg; the ZrH2 powder has a size of 3 μm and a mass of 0.14 kg.

[0133] The aluminum alloy powder preparation process, modeling process, parameters in the 3D printing process, and sandblasting treatment are the same as in Example 1. The difference is that the aging heat treatment in this example is carried out in a conventional heat treatment furnace at a temperature of 400°C for 3 hours.

[0134] This embodiment can integrally mold a child safety seat frame that meets performance requirements. The resulting target aluminum alloy part is crack-free, has a tensile strength of 500 MPa, a yield strength of 460 MPa, an elongation of 13%, and a density of 2.713 g / cm³. 3 The density is 99.5% and the specific strength is 0.184 N·m / kg. Taking a child safety seat frame of the same shape and size made of 780 MPa ultra-high strength steel as a reference, its specific strength is about 0.1 N·m / kg. The weight reduction rate of the aluminum alloy child safety seat frame in this embodiment is about 84%.

[0135] Example 5

[0136] The composition ratio, preparation process, modeling process, heat treatment and sandblasting process of the aluminum alloy used for the child safety seat frame in this embodiment are the same as those in Embodiment 1.

[0137] The selective laser melting (SLM) parameters were: scanning power of 360W, scanning speed of 800mm / s, powder thickness of 0.1mm, and scanning spacing of 0.1mm. The substrate was preheated to 50℃.

[0138] This embodiment allows for the one-piece molding of a child safety seat frame that meets performance requirements. The resulting target aluminum alloy part is crack-free, with a tensile strength of 461 MPa, a yield strength of 405 MPa, an elongation of 14.5%, and a density of 2.743 g / cm³. 3 The density is 99.9% and the specific strength is 0.168 N·m / kg. Taking a child safety seat frame of the same shape and size made of 780 MPa ultra-high strength steel as a reference, its specific strength is about 0.1 N·m / kg. The weight reduction rate of the aluminum alloy child safety seat frame in this embodiment is about 68%.

[0139] Example 6

[0140] A method for molding an aluminum alloy child safety seat frame includes the following steps:

[0141] Step 1: Prepare aluminum alloy powder for child safety seat frames;

[0142] S11: Weigh a certain amount of pure metal ingots and / or alloy ingots, Si powder, and ZrH2 powder according to the aluminum alloy composition ratio;

[0143] The aluminum alloy composition, by mass percentage, is: Mg: 3.5%, Zr: 1.2%, Mn: 0.74%, Si: 1.2%, Fe: 0.03%, Ti: 0.02%, with the remainder being Al and non-removable impurity elements.

[0144] According to the component ratio, weigh out 10 kg of Al ingots, Mg ingots, Zr ingots, Mn ingots and Ti ingots with a purity of 99.9% or higher;

[0145] The Si powder has a size of 3 μm and a mass of 0.11 kg; the ZrH2 powder has a size of 3 μm and a mass of 0.11 kg.

[0146] S12: Obtain alloy ingots by vacuum melting pure metal ingots and alloy ingots;

[0147] S121: Place the weighed aluminum ingots into the crucible of the vacuum intermediate frequency induction furnace, evacuate the furnace, and when the vacuum degree is less than 1*10... - 2When Pa, heating begins and argon gas is introduced to create a positive pressure environment inside the furnace; the heating rate is 20℃ / s, and heating is stopped after the furnace temperature reaches 700~850℃, and the furnace is held at that temperature for 1 hour.

[0148] S122: According to the melting point of the billet, other pure metal ingots and alloy ingots are added in order from high to low. After the alloy ingot is completely melted, hexachloroethane is added to degas it. The mixture is stirred by electromagnetic stirring at a speed of 300 r / min to make the elements evenly mixed. After holding and calming for 30 min, the casting begins. The casting temperature is 800℃ and the casting alloy flow rate is 10 kg / min to obtain the pre-alloyed ingot.

[0149] S13: The pre-alloyed ingot is powdered by argon atomization, with an atomization pressure of 3MPa and an atomization temperature of 780℃, to obtain the first pre-alloyed powder.

[0150] S14: The first pre-alloyed powder is mixed with Si powder and ZrH2 powder by a three-dimensional powder mixer or ball mill to obtain the second pre-alloyed powder. The speed of the three-dimensional powder mixer or ball mill is 15 r / min. During the powder mixing process, zirconia balls with a mass ratio of 25% are added as the powder mixing medium. The powder mixing time is 5 h. After the powder mixing is completed, the zirconia balls are removed.

[0151] S15: The second pre-alloyed powder is processed through a mesh sieve to obtain a third pre-alloyed powder with a size of 3-53 μm and a near-spherical shape;

[0152] S16: Vacuum drying is performed on the near-spherical third pre-alloy powder with a size of 3-53 μm obtained by sieving to obtain aluminum alloy powder; the drying temperature is 100℃ and the drying time is 6h.

[0153] Steps 2-6 are the same as in Example 1.

[0154] This embodiment can integrally mold a child safety seat frame that meets performance requirements. The resulting target aluminum alloy part is crack-free, with a tensile strength of 458 MPa, a yield strength of 404 MPa, an elongation of 14%, and a density of 2.743 g / cm³. 3 The density is 99.9% and the specific strength is 0.167 N·m / kg. Taking a child safety seat frame of the same shape and size made of 780 MPa ultra-high strength steel as a reference, its specific strength is about 0.1 N·m / kg. The weight reduction rate of the aluminum alloy child safety seat frame in this embodiment is about 67%.

[0155] Comparative Example 1

[0156] The aluminum alloy composition of the child safety seat frame in this comparative example, by mass percentage, is: Mg: 1.0%, Mn: 0.15%, Si: 0.6%, Fe: 0.7%, Ti: 0.15%, with the remainder being Al and non-removable impurity elements.

[0157] According to the component ratio, weigh out 22 kg of Al ingots, Mg ingots, Mn ingots, Fe ingots, Ti ingots and Al-Mg ingots with a purity of 99% or higher;

[0158] The Si powder has a size of 3μm and a mass of 0.13Kg.

[0159] The remaining steps and process parameters are the same as in Example 1.

[0160] The child safety seat frame in this comparative example has a tensile strength of 198 MPa, a yield strength of 145 MPa, an elongation of 4%, a density of 98%, and exhibits localized cracking. The microstructure is shown in the diagram below. Figure 3 As shown. The Mg, Mn, and Fe contents of this comparative example are not within the range required by this invention, and it does not contain elements such as Sc, Zr, Er, and Y, which does not meet the requirements of this invention. The resulting child safety seat frame has poor printing performance and an elongation of only 4%, which cannot meet the performance requirements of a child safety seat frame, and it also has cracks that render it unusable.

[0161] Comparative Example 2

[0162] The difference between the child safety seat frame molding process in this comparative example and Example 1 lies in the selective laser melting (SLM) printing parameters: scanning power of 150W, scanning speed of 2000mm / s, powder thickness of 0.5mm, and scanning spacing of 0.5mm. The remaining steps and parameters are the same as in Example 1.

[0163] In the molding process of this comparative child safety seat frame, the selective laser melting (SLM) printing parameters did not meet the requirements of this invention. The resulting aluminum alloy child safety seat frame had a tensile strength of 355 MPa, a yield strength of 281 MPa, an elongation of 12%, and a density of 99.0%. Under the same composition, the strength of the aluminum alloy obtained in Example 1 was about 19% higher than that of the aluminum alloy material obtained in Comparative Example 2, and Example 1 showed significant weight reduction.

[0164] Comparative Example 3

[0165] The difference between the child safety seat frame molding process in this comparative example and that in Example 1 lies in the aluminum alloy powder preparation process; the remaining steps and parameters are the same as in Example 1.

[0166] The powder preparation process of the aluminum alloy powder in this comparative example is as follows:

[0167] S11: Weigh a certain amount of pure metal ingots and / or alloy ingots according to the aluminum alloy composition ratio;

[0168] The aluminum alloy composition, by mass percentage, is as follows: Mg: 3.5%, Zr: 1.2%, Mn: 0.74%, Si: 1.2%, Sc: 0.30%, Fe: 0.03%, Ti: 0.02%, with the remainder being Al and non-removable impurity elements.

[0169] According to the component ratio, weigh out a total of 30 kg of Al ingots, Mg ingots, Zr ingots, Mn ingots, Ti ingots, Al-Sc ingots and Al-Si ingots with a purity of 99% or higher.

[0170] S12: Obtain pre-alloyed ingots by vacuum melting pure metal ingots and alloy ingots;

[0171] S121: Place the weighed aluminum ingots into the crucible of the vacuum intermediate frequency induction furnace, evacuate the furnace, and when the vacuum degree is less than 1*10... - 2 At Pa, heating begins and argon gas is introduced to create a positive pressure environment inside the furnace; the heating rate is 15℃ / s, and heating is stopped after the furnace temperature reaches 700~850℃, and the furnace is held at that temperature for 1 hour.

[0172] S122: According to the melting point of the billet, other pure metal ingots and alloy ingots are added in order from high to low. After the alloy ingot is completely melted, hexachloroethane is added to degas the ingot. The mixture is stirred by electromagnetic stirring at a speed of 200 r / min to make the elements evenly mixed. After holding and settling for 30 minutes, the casting begins. The casting temperature is 750℃ and the casting alloy flow rate is 5 kg / min to obtain the pre-alloyed ingot.

[0173] S13: The pre-alloyed ingot is powdered by argon atomization at a pressure of 2.5 MPa and a temperature of 750°C to obtain pre-alloyed powder.

[0174] S14: The pre-alloyed powder is processed through a mesh sieve to obtain pre-alloyed powder with a size of 3-53 μm and a near-spherical shape;

[0175] S15: Vacuum drying is performed on the pre-alloyed powder with a size of 3-53 μm and a near-spherical shape obtained by sieving; the drying temperature is 100℃ and the drying time is 6h.

[0176] In the molding process of the child safety seat frame in this comparative example, the preparation process of aluminum alloy powder is different from that of this invention. The resulting aluminum alloy child safety seat frame has a tensile strength of 465 MPa, a yield strength of 420 MPa, an elongation of 6%, and a density of 99.6%. The elongation of this comparative example is too low and cannot meet the performance requirements of the child safety seat frame.

[0177] Comparative Example 4

[0178] The difference between the child safety seat frame forming process in this comparative example and that in Example 1 is that after obtaining the first child safety seat frame in step 4, hot isostatic pressing or ordinary heat treatment is not performed; instead, sandblasting is performed directly to obtain the child safety seat frame. The remaining steps and parameters are the same as in Example 1.

[0179] The child safety seat frame of this comparative example is formed without hot isostatic pressing or ordinary heat treatment. The resulting aluminum alloy child safety seat frame has a tensile strength of 302 MPa, a yield strength of 222 MPa, an elongation of 24%, and a density of 99.6%. The aluminum alloy of this comparative example has excellent toughness, but its strength is too low to meet the performance requirements of the child safety seat frame.

[0180] Table 1. Aluminum alloy composition (wt, %) of the examples and comparative examples

[0181] serial number Mg Zr Mn Si Sc Er Y Ti Fe Al Example 1 3.5 1.2 0.74 1.2 0.30 - - 0.02 0.03 margin Example 2 4.5 0.45 1.2 0.1 0.35 0.15 0.15 0.01 0.03 margin Example 3 5.0 0.7 0.74 1.5 0.72 - 0.15 0.02 0.02 margin Example 4 5.0 0.7 0.74 1.5 0.72 - 0.15 0.02 0.02 margin Example 5 3.5 1.2 0.74 1.2 0.30 - - 0.02 0.03 margin Example 6 3.5 1.2 0.74 1.2 0.30 - - 0.02 0.03 margin Comparative Example 1 1.0 - 0.15 0.6 - - - 0.15 0.7 margin Comparative Example 2 3.5 1.2 0.74 1.2 0.30 - - 0.02 0.03 margin Comparative Example 3 3.5 1.2 0.74 1.2 0.30 - - 0.02 0.03 margin Comparative Example 4 3.5 1.2 0.74 1.2 0.30 - - 0.02 0.03 margin

[0182] Table 2. Aluminum alloy forming process parameters for the examples and comparative examples.

[0183]

[0184]

[0185]

[0186] Table 3 Mechanical properties of aluminum alloys in the examples and comparative examples

[0187]

[0188] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for forming an aluminum alloy child safety seat frame, characterized in that, Includes the following steps: Step 1: Prepare aluminum alloy powder for molding child safety seat frames. The composition ratio of the aluminum alloy powder, by mass percentage, is: Mg: 3.0-5.5%, Zr: 0.15-1.25%, Mn: 0.74-1.2%, Si: 0.1-2.5%, Sc: 0.15-0.75%, Ti≤0.5%, Fe≤0.4%, Er≤0.5%, Y≤0.5%, with the remainder being Al and non-removable impurity elements. Step 2: Design the dimensions and shape of the child safety seat frame, and create a model using 3D modeling software to obtain the child safety seat frame model; Step 3: Convert the child safety seat frame model file to STL format, define the printing direction, determine the number of printing layers and spacing using slicing software, and obtain the slice file; Step 4: Import the sliced ​​file into the 3D printer, input the printing parameters, and 3D print to obtain the first child safety seat frame; Step 5: Perform hot isostatic pressing or ordinary heat treatment on the first child safety seat frame to obtain the second child safety seat frame; Step 6: Perform sandblasting on the second child safety seat frame 1 to 3 times to obtain the child safety seat frame; Step 1 includes: S11: Weigh a certain amount of pure metal ingots and / or alloy ingots, Si powder, and ZrH2 powder according to the aluminum alloy composition ratio; S12: Obtain pre-alloyed ingots by vacuum melting pure metal ingots and alloy ingots; S13: Obtain the first pre-alloy powder by atomizing the pre-alloyed ingot; S14: Powder mixing: The first pre-alloyed powder is mixed with Si powder and ZrH2 powder using a three-dimensional powder mixer or ball mill to obtain the second pre-alloyed powder. S15: The second pre-alloyed powder is sieved through a sieve to obtain a third pre-alloyed powder that meets the size and shape requirements; S16: Vacuum drying is performed on the third pre-alloyed powder obtained by sieving that meets the size and shape requirements to obtain aluminum alloy powder; In step S11, the particle size of the Si powder and ZrH2 powder is 2-5 μm; In step S14, the powder mixing process is as follows: Zirconia balls are added as a powder mixing medium, and the first pre-alloyed powder is mixed with Si powder and ZrH2 powder through a three-dimensional powder mixer or ball mill. The rotation speed of the three-dimensional powder mixer or ball mill is 10-20 r / min, the mixing time is 2-10 h, and the mass ratio of zirconium oxide in the zirconium oxide balls is 15-25%. In step 5, the aging temperature of the ordinary heat treatment is 360-520℃, and the time is 2-6h; the temperature of the hot isostatic pressing is 360-520℃, the pressure is 60-150MPa, and the time is 2-6h; through step 5, the precipitation of dispersed phases Al3Sc, Al3(Sc,Zr), Al3Zr, and Mg2Si in the microstructure of the aluminum alloy is promoted; The aluminum alloy child safety seat frame has a tensile strength ≥450MPa, a yield strength ≥400MPa, an elongation ≥13%, a density ≥99.5%, a specific strength ≥0.16N·m / kg, and a weight reduction rate of over 60%.

2. The molding method according to claim 1, characterized in that, Step 2 includes: S21: Design the dimensions and shape of the target child safety seat frame; S22: Based on the size and shape of the target child safety seat frame, use the sketching tool of the modeling software to draw the basic shape and size of the child safety seat frame on a plane; S23: Using the feature tools of modeling software, the sketch is converted into a three-dimensional solid to obtain the first child safety seat frame model; S24: Use finite element simulation software to simulate and analyze the stress field, strain field, and mass of the first child safety seat frame model; S25: Based on the simulation analysis results, determine whether the model analysis results meet the stopping iteration condition. If they do, determine the child safety seat frame model. If they do not meet, perform structural optimization on the first child safety seat frame model to obtain the second child safety seat frame model. S26: Simulate and analyze the stress field, strain field, and mass of the second child safety seat frame model. Based on the simulation analysis results, determine whether the model analysis results meet the stopping iteration condition. If they do, the second child safety seat frame model is determined to be the final child safety seat frame model. If not, perform structural optimization on the second child safety seat frame model and repeat the simulation analysis until the Nth child safety seat frame model obtained after N iterations meets the stopping iteration condition, which is then the final child safety seat frame model.

3. The molding method according to claim 2, characterized in that, In step S25, the stopping iteration condition is: simultaneously satisfying the ratio of the equivalent stress of the Nth child safety seat frame model to the stress of the target child safety seat frame ≥ 1, and the mass ratio of the Nth child safety seat frame model to the target child safety seat frame ≤ 0.

4.

4. The molding method according to claim 1, characterized in that, In step 4, the 3D printing is selective laser melting, and the substrate of the selective laser melting equipment is preheated at a temperature of 50-320°C.

5. The molding method according to claim 4, characterized in that, The selective laser melting parameters are: scanning power of 200-400W, scanning speed of 400-1200mm / s, powder thickness of 0.03-0.1mm, and scanning spacing of 0.09-0.2mm.

6. The molding method according to claim 1, characterized in that, In step 5, the aging temperature of the ordinary heat treatment is 400-520℃, and the time is 2-6h; the temperature of the hot isostatic pressing is 360-520℃, the pressure is 100-150MPa, and the time is 2-6h.

7. An aluminum alloy child safety seat frame formed by the molding method according to any one of claims 1-6.

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