A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling

Abstract

The present invention discloses a method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling. The foamable melt is filled into alloy square tubes in a liquid or semi-solid state by die-casting, and then semi-solid rolling is carried out to obtain a foamed sandwich structure, and finally a foam metal sandwich panel with a metallurgical bonding interface is obtained by heat preservation foaming. The method of die-casting combined with semi-solid rolling in the present invention directly presses the foamable melt into the alloy square tubes, inhibits the decomposition of the blowing agent in the foamable melt, ensures the foaming ability of the foamable melt, and at the same time, the continuous stirring during the die-casting process and the semi-solid rolling ensure the core layer structure formed by the foamable melt in the foamed sandwich structure and the strength and thickness uniformity of the alloy square tube panel, improves the overall mechanical properties of the foam metal sandwich panel, and the whole process flow is short, the cost is low, the structure and properties of the prepared material are controllable, the product yield is high, and the application range of the foam metal sandwich panel is broadened.

Description

Technical Field

[0001] The present invention belongs to the technical fields of metal casting and semi-solid rolling, and particularly relates to a method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling. Background Art

[0002] A layered composite structure obtained by using a foam metal as the core layer and a dense metal plate as the face plate through physical or metallurgical connection processes is simply referred to as a foam metal sandwich panel. This layered composite structure combines the excellent characteristics of the foam core layer and the metal face plate. While meeting the requirements of lightweight, it exhibits characteristics such as high specific stiffness, high specific strength, shock absorption and energy absorption, and has broad application prospects in the fields of transportation, aerospace, and construction.

[0003] According to the interface bonding form, the preparation of foam metal sandwich panels is mainly divided into two categories: physical connection methods and metallurgical connection methods. Physical connection methods mainly include bolt connection, adhesive bonding, riveting and other methods. Metallurgical connection methods can be divided into two categories according to their forming characteristics: foaming first and then connecting, and connecting first and then foaming. The former uses means such as brazing and friction stir welding to achieve the connection between the face plate and the foam core layer; the latter first uses powder metallurgy or liquid phase composite processes to prepare a foamable preform, then uses hot pressing or rolling technology to connect it with the face plate, and finally obtains a foam metal sandwich panel through heat preservation and foaming. The industrial preparation of foam metal sandwich panels with metallurgical bonding interfaces is still the focus of current attention.

[0004] The invention patent with the publication number CN108705084A specifically discloses a method for preparing a large-sized foam aluminum sandwich panel for industrial use by powder encapsulation rolling. This method first uniformly mixes aluminum powder / aluminum alloy powder, silicon powder, copper powder, etc. with a foaming agent and sets it aside. Then, an aluminum alloy pipe or plate is processed into a tubular cavity with one end sealed. Finally, the composite powder is filled into the tubular cavity, and a foamable sandwich structure is obtained through cold rolling, hot rolling, and heat treatment, and a foam aluminum sandwich panel is obtained through heat preservation and foaming. There is also German patent DE4426627C2 for preparing foam aluminum sandwich panels based on powder metallurgy technology. The powder metallurgy method can strictly control the ratio of metal powder and additives to obtain a uniform pore structure. However, the high raw material cost and high requirements for machining ability of this method limit its industrial market.

[0005] For the above reasons, the invention patent with the publication number CN1669688A, based on the idea of melt foaming, specifically discloses a continuous casting and rolling production method of metallic foam, and prepares an aluminum foam sandwich panel by means of secondary melt foaming. First, 45# steel and pure aluminum are melted at 1450°C and 720°C respectively, then a viscosity enhancer and a foaming agent are added to the aluminum melt, and they are uniformly dispersed in the aluminum melt by stirring; then the 45# steel and the aluminum melt are poured into a four-baffle vertical two-high rolling mill and rolled in a semi-solid or solid state to obtain a strip of the precursor of the steel / aluminum / steel sandwich panel before foaming. This strip is then reheated and foamed to obtain a steel / aluminum foam / steel composite aluminum foam sandwich panel. This method realizes the continuous preparation of the steel / aluminum / steel composite aluminum foam sandwich panel, but the panel and the core layer need to be melted simultaneously. Especially for the high-melting-point panel, it increases the requirement for the melting capacity of the equipment and makes the process complicated, and it is difficult to ensure the thickness uniformity of the panel.

[0006] Based on this, the invention patent with the publication number CN108326044A specifically discloses a method for preparing an aluminum foam sandwich panel by liquid-phase mixing rolling and cladding. First, an aluminum alloy is melted and kept warm, a stabilizer and a foaming agent are added thereto and stirred evenly, and then it is quenched at a certain quenching rate for a period of time to obtain a foamable preform; then, the foamable preform is embedded in an aluminum sleeve and rolled to obtain a foamable sandwich structure; finally, the above-mentioned foamable sandwich structure is placed in an infrared foaming furnace for rapid foaming to obtain an aluminum / aluminum composite aluminum foam sandwich panel with a metallurgical bonding interface. This method greatly reduces the production cost while effectively ensuring the thickness uniformity of the metallic foam sandwich panel, but the preparation process of the preform inevitably causes the decomposition of the foaming agent and the phenomenon of melt stratification, which affects the uniformity of the foam core layer structure.

[0007] The invention patent with the publication number CN114406029A specifically discloses a method for preparing a continuous density gradient aluminum foam sandwich panel. In this method, a foamable melt is directly cast and rolled to obtain a foamable preform strip, then it is heat-insulated and foamed to obtain an aluminum foam material, and finally the obtained aluminum foam material is hot-rolled to densify the upper and lower surfaces of the aluminum foam material to obtain an aluminum foam sandwich panel. This method can realize the integrated casting and rolling forming of the continuous density gradient metallic foam sandwich panel, but during the process of forming the panel by hot rolling, the integrity of the core layer structure and the thickness uniformity of the panel need to be strictly controlled by regulating the rolling process parameters, and it is difficult to effectively ensure the strength of the formed panel. At the same time, the process has high requirements for processing accuracy. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling in view of the deficiencies of the above-mentioned prior art. This method uses the method of die casting combined with semi-solid rolling to directly press the foamable melt into the alloy square tube for semi-solid rolling and heat preservation foaming, which ensures the foaming ability of the foamable melt, and further ensures the strength and thickness uniformity of the core layer structure and the panel in the foamable sandwich structure, improves the overall mechanical properties of the foam metal sandwich panel, and solves the problems of low interfacial bonding strength between the panel and the core layer, uneven thickness, complex process and high cost caused by the existing clad rolling.

[0009] To solve the above technical problems, the technical solution adopted by the present invention is: A method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling, characterized in that the foamable melt is filled into the alloy square tube by die casting in a liquid or semi-solid state, and then semi-solid rolling is carried out to obtain a foamed sandwich structure, and then a foam metal sandwich panel with a metallurgical bonding interface is obtained through heat preservation foaming.

[0010] The above-mentioned method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that the preparation of the foamable melt is carried out in a closed cavity, and argon is introduced throughout the preparation process as a protective atmosphere.

[0011] The above-mentioned method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that the semi-solid rolling is carried out by an inclined rolling mill, the number of rolling passes is 1 to 3 passes, the reduction per pass is 5% to 25%, the rolling speed is 0.8 m / min to 1.1 m / min, and rapid cooling is carried out after rolling to obtain a foamable sandwich structure. By controlling the multi-pass rolling process, the thickness of the core layer and the panel of the foam metal sandwich panel is regulated, and the overall mechanical properties of the foam metal sandwich panel are improved.

[0012] The above-mentioned method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that the preparation method of the foam metal sandwich panel includes the following steps:

[0013] Step 1: Add an alloy into a closed furnace cavity, and fill argon as a protective atmosphere, then raise the temperature in the furnace cavity above the melting point of the alloy, and wait for the alloy to completely melt and keep warm for 15 min to 30 min to form an alloy melt;

[0014] Step 2: Under the argon protective atmosphere, cool down the alloy melt formed in Step 1, then add a foaming agent and stir evenly, the stirring speed is 1500 rpm to 2500 rpm, and the stirring time is 1 min to 3 min to form a foamable melt;

[0015] Step 3: Select an alloy square tube, and treat the oil stains and mill scale on the inner wall of the alloy square tube by mechanical grinding and chemical treatment until a fresh surface appears. Then seal one end of the alloy square tube and preheat it in a vacuum furnace.

[0016] Step 4: Under the state of continuous stirring, adjust the air pressure inside the furnace cavity and simultaneously open the bottom valve of the furnace. Under the action of gravity and air pressure, press the foamable melt formed in Step 2 into the preheated alloy square tube in Step 3, and then send it into a rolling mill for semi-solid rolling to obtain a foamed sandwich structure through rapid cooling.

[0017] Step 5: Cut the foamed sandwich structure obtained in Step 4 and place it in a foaming mold in a muffle furnace for heat preservation and foaming. Select the foaming temperature according to the core layer alloy and keep it warm for 2 min to 10 min to obtain a foam metal sandwich panel with a metallurgical bonding interface.

[0018] In the above method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling, it is characterized in that the alloy in Step 1 is aluminum or aluminum alloy, the temperature in the furnace cavity rises to 700 °C to 750 °C, the temperature is reduced to 600 °C to 700 °C in Step 2, a graphite stirring paddle is used for stirring, the foaming agent is TiH2, and it is oxidized at 480 °C for 1 h to 5 h before adding the foaming agent; or the alloy in Step 1 is magnesium or magnesium alloy, the temperature in the furnace cavity rises to 680 °C to 730 °C, the temperature is reduced to 600 °C to 680 °C in Step 2, a stainless steel stirring paddle is used for stirring, and the foaming agent is MgCO3 or CaCO3. Based on the fact that a reaction is likely to occur between aluminum or aluminum alloy and iron under the heat generated by stirring, the present invention uses a graphite stirring paddle to avoid introducing impurities into the alloy melt due to the reaction; magnesium or magnesium alloy has high oxygen affinity, and it is found in the research process of the present invention that using a graphite stirring paddle will accelerate the oxidation of the magnesium or magnesium alloy melt, so a stainless steel stirring paddle is used.

[0019] In the above method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling, it is characterized in that the alloy square tube in Step 3 is an aluminum alloy square tube with an overall thickness of 8 mm to 12 mm and a wall thickness of 1 mm to 3 mm. The treatment is to polish the inner surface of the aluminum alloy square tube with a steel brush, then pickle it with dilute hydrochloric acid for 2 min to 5 min, quickly take it out for ultrasonic cleaning and vacuum drying. The preheating temperature is 200 °C to 400 °C and the time is 0.5 h to 1 h; or the alloy square tube is a steel square tube with an overall thickness of 8 mm to 12 mm and a wall thickness of 1 mm to 3 mm. The treatment is to polish the inner surface of the aluminum alloy square tube with a steel brush, then pickle it with dilute hydrochloric acid for 2 min to 5 min, quickly take it out for ultrasonic cleaning and vacuum drying. The preheating temperature is 400 °C to 600 °C and the time is 0.5 h to 1 h.

[0020] The above method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that in step two, SiC is added as a stabilizer and a thickening agent and stirred evenly.

[0021] The above method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that in step three, the sealing method is welding or riveting.

[0022] The above method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that in step four, the speed of continuous stirring is 1500 rpm to 2500 rpm, and the internal air pressure of the furnace chamber is adjusted to 1 MPa to 3 MPa; the rolling is carried out by an inclined rolling mill, and the connecting line of the roll shafts of the inclined rolling mill forms an angle of 15° with the normal direction. During the rolling process, cooling water is passed through the rolls, so that the foamable melt core layer in the alloy square tube solidifies after the first pass of rolling and forms a metallurgical bonding interface with the alloy square tube; the porosity of the foamable sandwich structure is less than 20%.

[0023] The above method for preparing a foam metal sandwich panel by die casting combined with semi-solid rolling is characterized in that in step five, the cutting is carried out by wire cutting or shearing; the core layer alloy is aluminum alloy and the foaming temperature is 680 °C to 750 °C, or the core layer alloy is magnesium alloy and the foaming temperature is 660 °C to 720 °C; after heat preservation and foaming, rapid cooling is carried out by water cooling. Usually, a limiting device is arranged in the foaming mold to limit the loaded cut foam sandwich structure, thereby controlling the thickness and flatness of the foam metal sandwich panel. At the same time, the strength of the foam core layer and the interface bonding strength in the foam metal sandwich panel can also be controlled by subsequent heat treatment.

[0024] The present invention has the following advantages compared with the prior art:

[0025] 1. The present invention adopts the method of die casting combined with semi-solid rolling. By using die casting, the foamable melt is directly pressed into the alloy square tube, which inhibits the decomposition of the foaming agent in the foamable melt, ensures the foaming ability of the foamable melt, and at the same time, the continuous stirring and semi-solid rolling during the die casting process ensure the core layer structure formed by the foamable melt in the foamable sandwich structure and the strength and thickness uniformity of the alloy square tube panel, improves the overall mechanical properties of the foam metal sandwich panel, and broadens the application range of the foam metal sandwich panel.

[0026] 2. In the die casting process of the present invention, the foamable melt is filled into the alloy square tube in a liquid or semi-solid state. The good fluidity of the foamable melt enables it to be in close contact with the alloy square tube panel, avoiding the phenomenon of interface oxidation and reduction of interface bonding strength during hot rolling due to the failure of close contact between interfaces in the existing preform cladding rolling technology.

[0027] 3. The gas pressure applied during the die-casting process of the present invention and the shear force generated by continuous stirring can effectively inhibit the decomposition of the foaming agent, further improving the foaming ability of the foamed sandwich structure.

[0028] 4. Different from the prior art where the foamable melt is cooled into a block and then subjected to clad rolling, in the method of the present invention, during the die-casting process, continuous stirring effectively avoids the stratification phenomenon of the foamable melt, especially the appearance of the foam layer, greatly improving the stability of the subsequent thermal insulation foaming process and the uniformity of the prepared foam metal sandwich panel.

[0029] 5. Different from the panel formed by liquid solidification and cell collapse in the prior art, the present invention uses alloy profiles as the panel, which can not only ensure excellent mechanical properties of the panel but also ensure the uniformity of the panel thickness.

[0030] 6. Based on the melt method, the present invention adopts the method of die-casting combined with semi-solid rolling, which greatly reduces the raw material cost compared with the powder method. At the same time, it avoids process steps such as cooling the foamable melt into a billet, surface treatment before preform rolling, and pre-bonding treatment before solid-phase rolling, simplifies the preparation steps, shortens the process flow, reduces the manufacturing cost, and the structure and properties of the foam metal sandwich panel are controllable, facilitating continuous production.

[0031] 7. The present invention first proposes to prepare the foamable melt in an argon protection environment, solves the safety problem of high-temperature preparation of low-melting-point metal melts such as foamable magnesium alloy melts, and broadens the material range of the foam metal sandwich panel.

[0032] 8. The present invention introduces a protective atmosphere into the furnace body of the closed cavity, reducing the oxygen content in the furnace body in contact with the alloy melt, and realizing the safe preparation of high-oxygen-affinity metals such as foam magnesium sandwich panels.

[0033] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Brief Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of the equipment for preparing the foam metal sandwich panel by die-casting combined with semi-solid rolling of the present invention.

[0035] Figure 2 It is a process flow chart of the equipment for preparing the foam metal sandwich panel by die-casting combined with semi-solid rolling of the present invention.

[0036] Description of the Reference Numerals

[0037] 1 - Alloy melt; 2 - Feeding valve; 3 - Feeding port;

[0038] 4 - Stirring device; 5 - Protective gas inlet; 6 - Gas valve;

[0039] 7 - Upper cover of the furnace cavity; 8 - Fastening bolt; 9 - Sealed furnace cavity;

[0040] 10 - Melting and heating furnace; 11 - Discharge valve; 12 - Discharge port;

[0041] 13 - Alloy square tube; 14 - Foamable melt; 15 - Inclined rolling mill;

[0042] 16 - Foaming heating device; 17 - Foamable sandwich structure; 18 - Foamed metal sandwich panel. Detailed implementation mode

[0043] As Figure 1 shown, the equipment for preparing the foamed metal sandwich panel by die - casting combined with semi - solid rolling of the present invention includes a melting and heating furnace 10 and a sealed furnace cavity 9 installed in the melting and heating furnace 10. The sealed furnace cavity 9 is connected to the upper cover 7 of the furnace cavity by fastening bolts 8. The upper cover 7 of the furnace cavity is respectively provided with a feeding port 3 and a protective gas inlet 5, and a feeding valve 2 and a gas valve 6 are correspondingly arranged on the feeding port 3 and the protective gas inlet 5. A stirring device 4 extending into the sealed furnace cavity 9 is also installed on the upper cover 7 of the furnace cavity. The bottom of the sealed furnace cavity 9 is provided with a discharge port 12, and a discharge valve 11 is arranged on the discharge port 12. An alloy square tube 13 for receiving the foamable melt 14 is placed at the outlet of the discharge port 12. An inclined rolling mill 15 is arranged at the end of the alloy square tube 13. A foaming heating device 16 for holding the foamable sandwich structure 17 is arranged on the outlet side of the inclined rolling mill 15.

[0044] Example 1

[0045] As Figure 2 shown, this example includes the following steps:

[0046] Step 1: Add ZL102 aluminum - silicon alloy into the sealed furnace cavity 9, open the gas valve 6 and fill argon as the protective atmosphere through the protective gas inlet 5. Then raise the temperature in the sealed furnace cavity 9 to 750 °C, wait for the ZL102 aluminum - silicon alloy to completely melt and keep it warm for 30 min to form alloy melt 1;

[0047] Step 2: Under the argon protective atmosphere, cool the alloy melt 1 formed in Step 1 to 700 °C. Then open the feeding valve 2 and add 1% of the total mass of the foamable melt 14 of metallic Mg as a viscosity - increasing agent through the feeding port 3, add 3% of the total mass of the foamable melt 14 and SiC with a particle size of 10 μm as a stabilizer and a viscosity - increasing agent. Use a stirring device 4 equipped with a graphite - material stirring paddle to stir evenly. The stirring speed is 1500 rpm and the stirring time is 5 min to form a composite melt;

[0048] The composite melt is further cooled to 640 °C, and then the feeding valve 2 is opened to add TiH2 foaming agent with a particle size of 50 μm, accounting for 1% of the total mass of the foamable melt 14, through the feeding port 3. Before the addition of the TiH2 foaming agent, it is oxidized at 480 °C for 5 h, and then uniformly stirred by a stirring device 4 equipped with a graphite stirring paddle at a stirring speed of 2500 rpm for 1 min to form the foamable melt 14;

[0049] Step 3: Select a 6063 aluminum alloy square tube with an overall thickness of 12 mm and a wall thickness of 3 mm as the alloy square tube 13. The inner surface of the alloy square tube 13 is polished with a steel brush, then pickled with 0.5 mol / L dilute hydrochloric acid for 2 min, quickly taken out and ultrasonically cleaned with ethanol for 5 min, vacuum dried in a vacuum drying oven, and then one end of the alloy square tube is riveted and sealed and sent into a vacuum furnace for preheating at 400 °C for 30 min;

[0050] Step 4: Adjust the stirring speed to 1500 rpm. Under the continuous stirring state, adjust the internal pressure of the closed furnace chamber 9 to 1 MPa, and at the same time open the bottom discharge valve 11. Under the action of gravity and gas pressure, the foamable melt 14 formed in Step 2 is pressed into the preheated alloy square tube 13 in Step 3 through the discharge port 12, and then sent into a two-roll inclined rolling mill 15 with an included angle of 15° between the rolling mill shaft connection line and the normal direction for semi-solid rolling. During the rolling process, the rolling mill is cooled with cooling water. The number of rolling passes is 3 passes, the reduction per pass is 5%, and the rolling speed is 0.8 m / min. After rapid cooling, a foamed sandwich structure 17 with a thickness of 10.28 mm, a porosity of 18%, and a metallurgical bonding interface is obtained;

[0051] Step 5: The foamed sandwich structure 17 obtained in Step 4 is trimmed by a shearing machine and then placed in a foaming mold with a limiting function in a muffle furnace, and heated by a foaming heating device 16 for heat preservation and foaming. It is kept at 680 °C for 10 min and then rapidly cooled by water cooling to obtain a foam metal sandwich panel 18 with a metallurgical bonding interface, an expansion ratio of 300%, and a thickness of 24 mm, that is, an aluminum panel foam aluminum sandwich panel.

[0052] Example 2

[0053] As Figure 2 shown, this example includes the following steps:

[0054] Step 1: Add ZL102 aluminum-silicon alloy into the closed furnace chamber 9, open the gas valve 6, and fill argon as a protective atmosphere through the protective gas inlet 5. Then raise the temperature in the closed furnace chamber 9 to 750 °C, wait for the ZL102 aluminum-silicon alloy to completely melt, and keep it warm for 15 min to form the alloy melt 1;

[0055] Step 2: Under an argon protection atmosphere, cool the alloy melt 1 formed in Step 1 to 600 °C, then open the feeding valve 2 and add, through the feeding port 3, metallic Mg accounting for 1% of the total mass of the foamable melt 14 as a viscosity-increasing agent, and add SiC with a particle size of 10 μm accounting for 3% of the total mass of the foamable melt 14 as a stabilizer. Use a stirring device 4 equipped with a graphite stirring paddle to stir evenly. The stirring speed is 2500 rpm, and the stirring time is 5 min to form a composite melt;

[0056] Further cool the composite melt to 640 °C, then open the feeding valve 2 and add, through the feeding port 3, a foaming agent TiH2 accounting for 1% of the total mass of the foamable melt 14 with a particle size of 50 μm. Before adding the foaming agent TiH2, it is oxidized at 480 °C for 1 h. Use a stirring device 4 equipped with a graphite stirring paddle to stir evenly. The stirring speed is 2500 rpm, and the stirring time is 3 min to form the foamable melt 14;

[0057] Step 3: Select a 6063 aluminum alloy square tube with an overall thickness of 8 mm and a wall thickness of 1 mm as the alloy square tube 13. Use a steel brush to polish the inner surface of the alloy square tube 13, then perform pickling with 0.5 mol / L dilute hydrochloric acid for 5 min. After quickly taking it out, perform ultrasonic cleaning with ethanol for 5 min, vacuum dry it in a vacuum drying oven, then rivet and seal one end of the alloy square tube and send it into a vacuum furnace for preheating at 200 °C for 60 min;

[0058] Step 4: Adjust the stirring speed to 2500 rpm. Under the continuous stirring state, adjust the internal air pressure of the closed furnace chamber 9 to 3 MPa. At the same time, open the bottom discharge valve 11. Under the action of gravity and air pressure, press the foamable melt 14 formed in Step 2 into the preheated alloy square tube 13 in Step 3 through the discharge port 12, and then send it into a two-roll inclined rolling mill 15 for semi-solid rolling. The number of rolling passes is 1 pass, the single-pass reduction is 25%, and the rolling speed is 1.1 m / min. After rapid cooling, a foamed sandwich structure with a thickness of 6 mm, a porosity of 9%, and a metallurgical bonding interface is obtained;

[0059] Step 5: Use wire cutting to trim the foamed sandwich structure 17 obtained in Step 4, then place it in a foaming mold with a limiting function in a muffle furnace, and use a foaming heating device 16 to heat and keep it warm for foaming. Keep it warm at 750 °C for 2 min, and after rapid cooling by water cooling, a foam metal sandwich panel 18 with a swelling ratio of 400% and a thickness of 24 mm and a metallurgical bonding interface, that is, an aluminum panel foam aluminum sandwich panel, is prepared.

[0060] Example 3

[0061] As Figure 2 shown, this example includes the following steps:

[0062] Step 1: Add ZL102 aluminum-silicon alloy into the sealed furnace chamber 9, open the gas valve 6 and fill argon as the protective atmosphere through the protective gas inlet 5. Then raise the temperature in the sealed furnace chamber 9 to 750 °C, wait for the ZL102 aluminum-silicon alloy to completely melt and keep it warm for 20 min to form an alloy melt 1.

[0063] Step 2: Under the argon protective atmosphere, cool the alloy melt 1 formed in Step 1 to 700 °C. Then open the feeding valve 2 and add 1% of the total mass of the expandable melt 14 of metallic Mg as a viscosity-increasing agent through the feeding port 3, and add 3% of the total mass of the expandable melt 14 with a particle size of 10 μm of SiC as a stabilizer and viscosity-increasing agent. Use a stirring device 4 equipped with a graphite stirring paddle to stir evenly, with a stirring speed of 1500 rpm and a stirring time of 5 min to form a composite melt.

[0064] Cool the composite melt further to 640 °C. Then open the feeding valve 2 and add 2% of the total mass of the expandable melt 14 with a particle size of 50 μm of the foaming agent TiH2 through the feeding port 3. And the foaming agent TiH2 is oxidized at 480 °C for 5 h before adding. Use a stirring device 4 equipped with a graphite stirring paddle to stir evenly, with a stirring speed of 2500 rpm and a stirring time of 1.5 min to form an expandable melt 14.

[0065] Step 3: Select a 45# steel square tube with an overall thickness of 10 mm and a wall thickness of 2 mm as the alloy square tube 13. Use a steel brush to polish the inner surface of the alloy square tube 13, then pickle it with 0.5 mol / L dilute hydrochloric acid for 3 min, quickly take it out and ultrasonically clean it with ethanol for 5 min, dry it in a vacuum drying oven, then weld and seal one end of the alloy square tube and send it into a vacuum furnace to preheat at 600 °C for 40 min.

[0066] Step 4: Adjust the stirring speed to 2000 rpm. Under the continuous stirring state, adjust the internal air pressure of the sealed furnace chamber 9 to 2 MPa. At the same time, open the bottom discharge valve 11. Under the action of gravity and gas pressure, press the expandable melt 14 formed in Step 2 into the preheated alloy square tube 13 in Step 3 through the discharge port 12, and then send it into a two-roll inclined rolling mill 15 for semi-solid rolling. The number of rolling passes is 1 pass, the single-pass reduction is 20%, and the rolling speed is 1.0 m / min. After rapid cooling, a foamed sandwich structure with a thickness of 8 mm and a porosity of 11% is obtained.

[0067] Step 5: Use a shearing machine to trim the edges of the foamed sandwich structure 17 obtained in Step 4, and then place it in a foaming mold with a limiting function in a muffle furnace. Use a foaming heating device 16 to heat it for heat preservation foaming. Keep it at 750 °C for 3 min, and then rapidly cool it by water cooling to obtain a foamed metal sandwich panel 18 with a metallurgical bonding interface, having an expansion ratio of 250% and a thickness of 20 mm, that is, a steel panel foam aluminum sandwich panel.

[0068] Example 4

[0069] As Figure 2 shown, this example includes the following steps:

[0070] Step 1: Add AZ91D magnesium alloy into the sealed furnace chamber 9, open the gas valve 6, and fill argon as a protective atmosphere through the protective gas inlet 5. Then raise the temperature in the sealed furnace chamber 9 to 730 °C. Wait for the AZ91D magnesium alloy to completely melt and keep it warm for 20 min to form an alloy melt 1;

[0071] Step 2: Under the argon protective atmosphere, cool the alloy melt 1 formed in Step 1 to 680 °C. Then open the feeding valve 2 and add SiC with a particle size of 10 μm, accounting for 3% of the total mass of the foamable melt 14, through the feeding port 3 as a stabilizer. Use a stirring device 4 equipped with a stainless steel stirring paddle to stir evenly. The stirring speed is 1500 rpm, and the stirring time is 5 min to form a composite melt;

[0072] Cool the composite melt further to 640 °C. Then open the feeding valve 2 and add a foaming agent MgCO3 with a particle size of 80 μm, accounting for 1.5% of the total mass of the foamable melt 14, through the feeding port 3. Use a stirring device 4 equipped with a stainless steel stirring paddle to stir evenly. The stirring speed is 1500 rpm, and the stirring time is 1.5 min to form a foamable melt 14;

[0073] Step 3: Select a 6063 aluminum alloy square tube with an overall thickness of 12 mm and a wall thickness of 2 mm as the alloy square tube 13. Use a steel brush to polish the inner surface of the alloy square tube 13, then pickle it with 0.5 mol / L dilute hydrochloric acid for 3 min. Quickly take it out and ultrasonically clean it with ethanol for 5 min. Vacuum dry it in a vacuum drying oven, then rivet and seal one end of the alloy square tube and send it into a vacuum furnace to preheat it at 400 °C for 40 min;

[0074] Step 4: Adjust the stirring speed to 2000 rpm. Under the condition of continuous stirring, adjust the internal air pressure of the sealed furnace chamber 9 to 2 MPa. Meanwhile, open the bottom discharge valve 11. Under the action of gravity and air pressure, press the foamable melt 14 formed in Step 2 into the preheated alloy square tube 13 in Step 3 through the discharge port 12, and then send it into the two-roll inclined rolling mill 15 for semi-solid rolling. The number of rolling passes is 2 passes, the reduction per pass is 20%, and the rolling speed is 0.9 m / min. After rapid cooling, a foamed sandwich structure with a thickness of 7.68 mm and a porosity of 10% is obtained.

[0075] Step 5: Use a shearing machine to trim the foamed sandwich structure 17 obtained in Step 4, and then place it in a foaming mold with a limiting function in a muffle furnace. Use the foaming heating device 16 to heat it for heat preservation and foaming. Keep it at 720 °C for 2 min, and after rapid cooling by water cooling, a foam metal sandwich panel 18 with a metallurgical bonding interface, an expansion ratio of 300%, and a thickness of 24 mm, that is, an aluminum panel foam magnesium sandwich panel, is obtained.

[0076] Example 5

[0077] As Figure 2 shown, this example includes the following steps:

[0078] Step 1: Add AZ91D magnesium alloy into the sealed furnace chamber 9, open the gas valve 6, and fill argon as a protective atmosphere through the protective gas inlet 5. Then raise the temperature in the sealed furnace chamber 9 to 680 °C. Wait for the AZ91D magnesium alloy to completely melt and keep it warm for 20 min to form an alloy melt 1.

[0079] Step 2: Under the argon protective atmosphere, cool the alloy melt 1 formed in Step 1 to 600 °C. Then open the feeding valve 2 and add SiC with a particle size of 10 μm, accounting for 3% of the total mass of the foamable melt 14, as a stabilizer and thickener through the feeding port 3. Use a stirring device 4 equipped with a stainless steel stirring paddle to stir evenly. The stirring speed is 1500 rpm, and the stirring time is 5 min to form a composite melt.

[0080] Cool the composite melt further to 640 °C. Then open the feeding valve 2 and add CaCO3, a foaming agent with a particle size of 80 μm, accounting for 1.5% of the total mass of the foamable melt 14, through the feeding port 3. Use a stirring device 4 equipped with a stainless steel stirring paddle to stir evenly. The stirring speed is 1500 rpm, and the stirring time is 1.5 min to form a foamable melt 14.

[0081] Step 3: Select a 6063 aluminum alloy square tube with an overall thickness of 12 mm and a wall thickness of 2 mm as the alloy square tube 13. Use a steel brush to polish the inner surface of the alloy square tube 13, then pickle it with 0.5 mol / L dilute hydrochloric acid for 3 min. Quickly take it out and ultrasonically clean it with ethanol for 5 min. Vacuum dry it in a vacuum drying oven. Then rivet and seal one end of the alloy square tube and send it into a vacuum furnace to preheat at 400 °C for 40 min;

[0082] Step 4: Adjust the stirring speed to 2000 rpm. Under continuous stirring, adjust the internal air pressure in the closed furnace chamber 9 to 2 MPa. At the same time, open the bottom discharge valve 11. Under the action of gravity and air pressure, press the foamable melt 14 formed in Step 2 into the preheated alloy square tube 13 in Step 3 through the discharge port 12. Then send it into a two-roll inclined rolling mill 15 for semi-solid rolling. The number of rolling passes is 2 passes, the reduction per pass is 20%, and the rolling speed is 0.9 m / min. After rapid cooling, a foamed sandwich structure with a thickness of 7.68 mm and a porosity of 11% is obtained;

[0083] Step 5: Use a shearing machine to trim the foamed sandwich structure 17 obtained in Step 4 and place it in a foaming mold with a limiting function in a muffle furnace. Use a foaming heating device 16 to heat and carry out heat preservation foaming. Keep it at 660 °C for 10 min and quickly cool it with water to obtain a foam metal sandwich panel 18 with a metallurgical bonding interface, an expansion ratio of 300%, and a thickness of 24 mm, that is, an aluminum panel foam magnesium sandwich panel.

[0084] As mentioned above, it is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any simple modification, change, and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling, characterized in that, The foamable melt is filled into an alloy square tube in a liquid or semi-solid state by die casting, then semi-solid rolling is carried out to obtain a foamed sandwich structure, and then heat preservation and foaming are carried out to obtain a foam metal sandwich panel with a metallurgical bonding interface; the preparation method of the foam metal sandwich panel includes the following steps: Step 1: Add an alloy into a closed furnace cavity, and fill argon as a protective atmosphere, then raise the temperature in the furnace cavity above the melting point of the alloy, wait for the alloy to completely melt and keep it warm for 15 min to 30 min to form an alloy melt; Step 2: Under the argon protective atmosphere, cool down the alloy melt formed in Step 1, then add a foaming agent and stir evenly, the stirring speed is 1500 rpm to 2500 rpm, and the stirring time is 1 min to 3 min to form a foamable melt; Step 3: Select an alloy square tube, treat the oil stains and oxide scales on the inner wall of the alloy square tube by mechanical grinding and chemical treatment until a fresh surface appears, then seal one end of the alloy square tube and preheat it in a vacuum furnace; Step 4: Under the state of continuous stirring, adjust the internal air pressure of the furnace cavity and at the same time open the bottom valve of the furnace. Under the action of gravity and air pressure, press the foamable melt formed in Step 2 into the preheated alloy square tube in Step 3, and then send it into a rolling mill for semi-solid rolling, and obtain a foamed sandwich structure after rapid cooling; the speed of the continuous stirring is 1500 rpm to 2500 rpm, adjust the internal air pressure of the furnace cavity to 1 MPa to 3 MPa, and cool the rolling rolls with cooling water during the rolling process, so that the core layer of the foamable melt in the alloy square tube solidifies after the first pass of rolling and forms a metallurgical bonding interface with the alloy square tube; Step 5: Cut the foamed sandwich structure obtained in Step 4 and place it in a foaming mold in a muffle furnace for heat preservation and foaming, select the foaming temperature according to the core layer alloy and keep it warm for 2 min to 10 min to obtain a foam metal sandwich panel with a metallurgical bonding interface.

2. The method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, The preparation of the foamable melt is carried out in a closed cavity, and argon is introduced throughout the preparation process as a protective atmosphere.

3. The method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, wherein, The semi-solid rolling is carried out by an inclined rolling mill, the number of rolling passes is 1 to 3 passes, the reduction per pass is 5% to 25%, the rolling speed is 0.8 m / min to 1.1 m / min, and a foamed sandwich structure is obtained after rapid cooling after rolling.

4. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, The alloy in Step 1 is aluminum or aluminum alloy, the temperature in the furnace cavity is raised to 700 °C to 750 °C, the temperature is lowered to 600 °C to 700 °C in Step 2, the stirring is carried out by a graphite stirring paddle, the foaming agent is TiH2, and the foaming agent is oxidized at 480 °C for 1 h to 5 h before adding; or the alloy in Step 1 is magnesium or magnesium alloy, the temperature in the furnace cavity is raised to 680 °C to 730 °C, the temperature is lowered to 600 °C to 680 °C in Step 2, the stirring is carried out by a stainless steel stirring paddle, and the foaming agent is MgCO3 or CaCO3.

5. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, In Step 3, the alloy square tube has an overall thickness of 8 mm to 12 mm and a wall thickness of 1 mm to 3 mm, and is an aluminum alloy square tube. The treatment is to polish the inner surface of the aluminum alloy square tube with a steel brush, then pickle it with dilute hydrochloric acid for 2 min to 5 min, quickly take it out for ultrasonic cleaning and vacuum drying. The preheating temperature is 200°C to 400°C, and the time is 0.5 h to 1 h; or the alloy square tube is a steel square tube with an overall thickness of 8 mm to 12 mm and a wall thickness of 1 mm to 3 mm. The treatment is to polish the inner surface of the aluminum alloy square tube with a steel brush, then pickle it with dilute hydrochloric acid for 2 min to 5 min, quickly take it out for ultrasonic cleaning and vacuum drying. The preheating temperature is 400°C to 600°C, and the time is 0.5 h to 1 h.

6. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, In Step 2, SiC is added as a stabilizer and a thickener and stirred evenly.

7. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, In Step 3, the sealing method is welding or riveting.

8. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, In Step 4, the rolling is carried out by an inclined rolling mill, and the connecting line of the roll shafts of the inclined rolling mill forms an angle of 15° with the normal direction; the porosity of the foamable sandwich structure is less than 20%.

9. A method for preparing a foam metal sandwich panel by die-casting combined with semi-solid rolling according to claim 1, characterized in that, In Step 5, the cutting is carried out by wire cutting or shearing; the core layer alloy is aluminum alloy, and the foaming temperature is 680°C to 750°C, or the core layer alloy is magnesium alloy, and the foaming temperature is 660°C to 720°C; after heat preservation and foaming, rapid cooling is carried out by water cooling.

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