A casting method for bimetallic castings

Abstract

The present invention proposes a casting method for a bimetallic casting, comprising: after grinding, alkali washing and pickling the surface of the inlay body of the solid inlay, pouring liquid metal through the pouring unit of the casting mold; when the surface temperature of the solid inlay is within the range of ±50°C of the liquidus line of the pouring metal, starting at least two ultrasonic vibration units to apply ultrasonic vibration for 5 to 180 seconds; when the surface temperature of the solid inlay is 0 to 50°C above the interface formation temperature of the bimetallic composite material, starting at least two ultrasonic vibration units to apply ultrasonic vibration for 3 to 80 seconds; when the surface temperature of the solid inlay drops to 50 to 200°C, taking out the solidified casting from the pouring device to obtain the bimetallic casting. This method overcomes the problem of the limitation of the action range of a single ultrasonic sound source, can simultaneously improve the strength of the matrix and interface of the bimetallic casting, a gap is provided between the end of the ultrasonic vibration mechanism and the solid inlay, the ultrasonic vibration mechanism does not need to be designed for resonant frequency matching with the solid inlay, and avoids damage due to power overload of the ultrasonic generator.

Description

Technical Field

[0001] The invention relates to the technical field of casting, and in particular to a casting method of a bimetallic casting. Background Art

[0002] Bimetallic composite materials can achieve the complementary performance of two metal materials, thus combining the unique performance advantages of two metals, and have great application potential and prospects in the fields of transportation, electronics 3C, etc. The bimetallic composite materials currently being gradually developed include magnesium / aluminum bimetal, magnesium / titanium bimetal, aluminum / steel bimetal, aluminum / copper bimetal, etc.

[0003] Methods for preparing bimetallic composite materials include plastic forming, welding forming and casting forming. Casting forming includes metal mold casting, sand casting, graphite mold casting and lost foam casting, which has absolute advantages in the preparation of low-cost, large-size and complex-shaped bimetallic components. However, casting forming has the problems of very coarse interface and matrix structure, interface oxide inclusions and more intermetallic compounds, which have an adverse effect on the bonding performance of bimetallic composite materials and seriously limit the development and application of bimetallic composite materials.

[0004] In view of the above problems, the invention patent with the publication number CN113333676A in the prior art discloses a device and application of ultrasonic-assisted lost foam casting of magnesium-aluminum bimetallic castings, which directly connects an ultrasonic vibration component and a solid inlay to apply ultrasonic vibration, eliminates the oxide film on the surface of the aluminum inlay, and also plays a role in dendrite crushing and grain refinement, thereby improving the organizational properties of the interface of the magnesium-aluminum bimetallic material. However, when the ultrasonic vibration component is directly connected to the solid inlay, the ultrasonic equipment needs to be designed to match the resonant frequency with the solid inlay, and there are requirements for the size and shape of the solid inlay, which increases the design cost on the one hand, and for large-sized bimetallic castings, there is also the possibility of damage due to overload of the ultrasonic generator power. On the other hand, this method uses a single ultrasonic sound source with a limited range of action, and cannot simultaneously improve and enhance the bimetallic matrix and interface strength. Summary of the invention

[0005] In view of this, the present invention proposes a casting method for bimetallic castings to solve the technical problems proposed in the above background technology that the ultrasonic vibration component is directly connected to the solid inlay, is not applicable to large-sized bimetallic castings, and cannot simultaneously improve and enhance the bimetallic matrix and interface strength.

[0006] The technical solution of the present invention is achieved in this way:

[0007] The present invention provides a casting method for a bimetallic casting, using a casting device for the bimetallic casting, the casting device comprising a casting mold, a solid inlay and an ultrasonic vibration unit; a cavity is formed in the casting mold; the solid inlay is pre-placed in the cavity; at least two ultrasonic vibration units are provided, the ultrasonic vibration units comprising an ultrasonic generator and an ultrasonic vibration mechanism, the ultrasonic generator is connected to the ultrasonic vibration mechanism, and is used to control the ultrasonic vibration mechanism to generate ultrasonic vibration; the ultrasonic vibration mechanism is installed on the casting mold, at least two ends of the ultrasonic vibration mechanism are distributed above, below and / or on the side of the solid inlay, and a gap is provided between the ends of the ultrasonic vibration mechanism and the solid inlay;

[0008] The casting method comprises:

[0009] After grinding, alkali washing and pickling treatment on the surface of the inlay body of the solid inlay, pouring liquid metal through the pouring unit of the casting mold;

[0010] When the surface temperature of the solid inlay is within the range of ±50°C of the liquidus of the casting metal, at least two of the ultrasonic vibration units are started to apply ultrasonic vibration for 5 to 180 seconds;

[0011] When the surface temperature of the solid inlay is 0 to 50° C. above the interface formation temperature of the bimetallic composite material, at least two of the ultrasonic vibration units are activated to apply ultrasonic vibration for 3 to 80 seconds;

[0012] When the surface temperature of the solid inlay drops to 50-200° C., the solidified casting is taken out from the pouring device to obtain a bimetallic casting.

[0013] On the basis of the above technical solution, preferably, the shape of the casting is a cube, and there are five ultrasonic vibration units, four of which are arranged on the four sides of the casting, and the other ultrasonic vibration unit is arranged on the top or bottom surface of the casting.

[0014] On the basis of the above technical solution, preferably, the ultrasonic vibration mechanism includes a transducer, a variable amplitude rod and a tool head; the transducer is electrically connected to the ultrasonic generator; the two ends of the variable amplitude rod are rigidly connected to the transducer and the tool head respectively; the end of the tool head away from the variable amplitude rod serves as the end of the ultrasonic vibration mechanism, and the tool head is connected to the casting mold.

[0015] On the basis of the above technical solution, preferably, the ultrasonic vibration unit is in a resonant state when working, and when the liquid metal melt used for pouring is a liquid magnesium alloy melt, the resonant frequency of the transducer is 12~28kHz.

[0016] On the basis of the above technical solution, preferably, when the liquid phase difference between the liquid metal melt and the solid inlay used for casting is less than or equal to 200°C, the power of the ultrasonic generator is 50~500W; when the liquid phase difference is greater than or equal to 200°C, the power of the ultrasonic generator is 500~5000W.

[0017] On the basis of the above technical solution, preferably, the casting mold includes an upper mold, a lower mold and a pouring unit, the upper mold and the lower mold are connected to form the mold cavity therebetween, and the pouring unit is connected to the mold cavity.

[0018] On the basis of the above technical solution, preferably, the solid inlay includes an inlay body, an auxiliary fixing structure and a temperature measuring thermocouple, the inlay body is rigidly connected to the auxiliary fixing structure, the auxiliary fixing structure is connected to the upper mold or the lower mold, and the temperature measuring thermocouple is installed on the inlay body.

[0019] On the basis of the above technical solution, preferably, if the casting device uses lost foam casting, the mold includes a pouring unit, a sand box, a foam model and sand, the pouring unit is connected to the foam model, the solid inlay is installed at the bottom of the sand box, the ultrasonic vibration unit is arranged in the sand box and connected to the side and / or top surface of the foam model, and the sand is filled in the blank area of ​​the sand box.

[0020] On the basis of the above technical solution, preferably, the casting mold also includes a vacuum diaphragm and a vacuum chamber, the vacuum diaphragm cover is arranged on the top of the sand box, the vacuum chamber is arranged at the bottom of the sand box and is connected to the sand box, and the vacuum chamber is used to connect to the vacuum extraction equipment.

[0021] The casting method of the bimetallic casting of the present invention has the following beneficial effects compared with the prior art:

[0022] (1) By distributing the ends of at least two of the ultrasonic vibration mechanisms above, below and / or to the sides of the solid inlay, the problem of the limited range of action of a single ultrasonic sound source is overcome, and the strength of the matrix and interface of the bimetallic casting can be improved at the same time. By providing a gap between the ends of the ultrasonic vibration mechanism and the solid inlay, the ultrasonic vibration mechanism is not directly connected to the solid inlay, and the ultrasonic vibration unit does not need to be designed to match the resonant frequency with the solid inlay, and the situation where the ultrasonic generator is damaged due to power overload can be avoided;

[0023] (2) There are five ultrasonic vibration units, four of which are arranged on four sides of the mold, so that the four ultrasonic vibration mechanisms are respectively located on the four sides of the solid inlay, and another ultrasonic vibration unit is arranged on the top or bottom surface of the mold, so that the ultrasonic vibration mechanism is located above or below the solid inlay, and ultrasonic vibration is applied to the surroundings and end faces of the solid inlay, thereby simultaneously improving the strength of the matrix and interface of the bimetallic casting;

[0024] (3) The resonant frequency of the transducer is 12-28 kHz, and the cavitation range generated by the ultrasonic wave in the liquid metal melt is larger, so the ultrasonic vibration effect is better, which can further enhance the strength of the matrix and interface of the bimetallic casting and improve the quality of the bimetallic casting;

[0025] (4) When the liquid phase difference between the liquid metal melt and the solid inlay used for casting is less than or equal to 200°C, the power of the ultrasonic generator is 50-500W; when the liquid phase difference is greater than or equal to 200°C, the power of the ultrasonic generator is 500-5000W. The above power range can ensure that the surface of the solid inlay will not be severely melted due to excessive power, while ensuring better vibration effect and improving stability and reliability;

[0026] (5) When the surface temperature of the solid inlay is within the range of ±50°C of the liquidus line of the casting metal, at least two of the ultrasonic vibration units are started to apply ultrasonic vibration for 5 to 180 seconds; when the surface temperature of the solid inlay is 0 to 50°C above the interface formation temperature of the bimetallic composite material, at least two of the ultrasonic vibration units are started to apply ultrasonic vibration for 3 to 80 seconds. By setting the above vibration time, it is avoided that the ultrasonic action time is insufficient to achieve the effect of refining the structure and breaking the interface oxide film, and it is avoided that the ultrasonic action time is too long, on the one hand, the thermal effect generated by the ultrasonic wave will cause the grains to grow, and on the other hand, it will cause the surface of the solid inlay body to melt excessively, causing the inlay body to lose its original shape characteristics and fail, thereby improving reliability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a three-dimensional diagram of a casting device for a bimetallic casting in the first embodiment of the present invention;

[0029] Figure 2 is a cross-sectional view of a casting device for a bimetallic casting in Embodiment 1 of the present invention;

[0030] Figure 3 It is a three-dimensional diagram of a casting device for a bimetallic casting in the second embodiment of the present invention;

[0031] Figure 4 It is a cross-sectional view of a casting device for a bimetallic casting in a second embodiment of the present invention;

[0032] Figure 5 It is a three-dimensional diagram of a casting device for a bimetallic casting in Embodiment 3 of the present invention;

[0033] Figure 6 It is a cross-sectional view of a casting device for a bimetallic casting in Embodiment 3 of the present invention;

[0034] Figure 7 The SEM test images of the bimetallic matrix structures of Application Example 1 and Comparative Example 1;

[0035] Figure 8 EBSD test images of bimetallic interface structures of Application Example 1 and Comparative Example 1;

[0036] Fig. 9 It is a schematic diagram of the process of the casting method of the bimetallic casting of the present invention.

[0037] Description of reference numerals: 1-ultrasonic vibration unit, 2-casting mold, 3-solid inlay;

[0038] 101 - ultrasonic generator, 102 - transducer, 103 - horn, 104 - tool head;

[0039] 201-upper mold, 202-lower mold, 203-pouring unit, 204-foam model, 205-sand box, 206-sand, 207-vibration table, 208-vacuum diaphragm, 209-vacuum chamber;

[0040] 301-inlay body, 302-auxiliary fixing structure, 303-temperature measuring thermocouple. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Embodiment 1

[0043] The present invention provides a bimetallic casting device suitable for metal mold casting and graphite mold casting, referring to Figure 1 and Figure 2 As shown, it includes a mold 2, a solid inlay 3 and an ultrasonic vibration unit 1, wherein:

[0044] A cavity is formed in the casting mold 2; the casting mold 2 comprises an upper mold 201, a lower mold 202 and a pouring unit 203; the upper mold 201 and the lower mold 202 are connected to form the cavity therebetween; the pouring unit 203 is connected to the cavity; a pouring hole of the pouring unit 203 is connected to the top of the cavity, and liquid metal melt is poured in a self-pouring manner; the casting mold 2 can be used for casting of liquid magnesium and magnesium alloys, liquid aluminum and aluminum alloys, liquid copper and copper alloys, liquid steel or liquid titanium alloys;

[0045] The solid inlay 3 is pre-placed in the mold cavity; the solid inlay 3 includes an inlay body 301, an auxiliary fixing structure 302 and a temperature measuring thermocouple 303, the inlay body 301 is rigidly connected to the auxiliary fixing structure 302, the auxiliary fixing structure 302 is connected to the upper mold 201, the auxiliary fixing structure 302 can use screws, and the top surface of the inlay body 301 is fixed to the top of the upper mold 201 by screws, the four side surfaces and the bottom surface of the inlay body 301 are free surfaces, the temperature measuring thermocouple 303 is installed on the inlay body 301, the temperature measuring thermocouple 303 is located at the top of the inlay body 301 and inserted into the mold cavity; the inlay body 301 can be a solid magnesium and magnesium alloy, solid aluminum and aluminum alloy, solid copper and copper alloy, solid steel or solid titanium and titanium alloy component;

[0046] At least two ultrasonic vibration units 1 are provided, and the ultrasonic vibration units 1 include an ultrasonic generator 101 and an ultrasonic vibration mechanism. The ultrasonic generator 101 is connected to the ultrasonic vibration mechanism and is used to control the ultrasonic vibration mechanism to generate ultrasonic vibrations. The ultrasonic vibration mechanism is installed on the mold 2, and at least two ends of the ultrasonic vibration mechanism are distributed below and / or to the side of the solid inlay 3, and a gap is provided between the ends of the ultrasonic vibration mechanism and the solid inlay 3. The ends of at least two ultrasonic vibration mechanisms are distributed on at least two of the five free surfaces of the solid inlay 3.

[0047] The casting device for bimetallic castings provided in the present embodiment overcomes the problem of limited action range of a single ultrasonic sound source by distributing the ends of at least two of the ultrasonic vibration mechanisms below and / or to the side of the solid inlay 3, and can simultaneously improve the strength of the matrix and interface of the bimetallic casting. A gap is provided between the end of the ultrasonic vibration mechanism and the solid inlay 3, the ultrasonic vibration mechanism is not directly connected to the solid inlay 3, the ultrasonic vibration unit 1 does not need to be designed to match the resonant frequency with the solid inlay 3, and the ultrasonic generator 101 can be prevented from being damaged due to power overload.

[0048] In some embodiments, the mold 2 has a cube shape, and five ultrasonic vibration units 1 are provided, wherein four of the ultrasonic vibration units 1 are provided on four sides of the mold 2, so that the four ultrasonic vibration mechanisms are respectively located on the four sides of the solid inlay 3, and another ultrasonic vibration unit 1 is provided on the bottom surface of the mold 2, so that the ultrasonic vibration mechanism is located below the solid inlay 3, and ultrasonic vibration is applied to the surroundings and bottom surface of the solid inlay 3, thereby simultaneously improving the strength of the matrix and interface of the bimetallic casting.

[0049] In some further embodiments, the ultrasonic vibration mechanism includes a transducer 102, a horn 103 and a tool head 104; the transducer 102 is electrically connected to the ultrasonic generator 101; the two ends of the horn 103 are rigidly connected to the transducer 102 and the tool head 104 respectively; the end of the tool head 104 away from the horn 103 serves as the end of the ultrasonic vibration mechanism, and the tool head 104 is connected to the mold 2. Five tool heads 104 are connected to the four side surfaces and the bottom surface of the lower mold 202, and can be flush with the inner wall of the lower mold 202 to more directly transmit the ultrasonic vibration to the liquid metal melt and improve the strength of the matrix. The angle between the axis of the tool head 104 and the surface of the inlay body 301 is 45~90°, so as to avoid the influence of the ultrasonic vibration mechanism on the structure of the mold 2 as much as possible. The ultrasonic energy is mainly concentrated on the end face of the tool head 104. When propagating in the liquid metal melt, the ultrasonic energy experiences nonlinear attenuation. The farther away from the end face of the ultrasonic tool head 104, the smaller the energy. Therefore, the distance between the tool head 104 and the surface of the inlay body 301 needs to be adjusted within a certain range based on experiments. Preferably, the distance between the end face of the ultrasonic tool head 104 and the surface of the inlay body 301 is 5 to 100 mm.

[0050] In some embodiments, the ultrasonic vibration unit 1 is in a resonant state when working, and the resonant frequency of the transducer 102 is 12~28kHz. For liquid magnesium alloy melt, its cavitation threshold is 1MPa. When the ultrasonic frequency is 18~22kHz, the cavitation range generated in the ultrasonic liquid metal melt is larger; and for other different types of liquid metal melts, the selection of ultrasonic frequency also needs to be adjusted within a certain range based on experiments. The resonant frequency of the transducer 102 is 12~28kHz, which can meet the requirements of generating a larger range of cavitation effects in different types of liquid metal melts. Therefore, the ultrasonic vibration effect is better, which can further enhance the strength of the matrix and interface of the bimetallic casting and improve the quality of the bimetallic casting.

[0051] In some embodiments, for two metals with similar liquidus lines, excessive ultrasonic power will cause serious melting of the surface of the solid inlay 3; and for two metals with large liquidus differences, too low ultrasonic power will not achieve a better effect. Therefore, the selection of ultrasonic power needs to be adjusted within a certain range according to the melting points of the inlay body 301 and the liquid metal melt. Therefore, preferably, when the liquidus difference between the liquid metal melt used for casting and the solid inlay 3 is less than or equal to 200°C, the power of the ultrasonic generator is 50~500W; when the liquidus difference is greater than or equal to 200°C, the power of the ultrasonic generator is 500~5000W. The setting of the above power range can ensure that the surface of the solid inlay 3 will not be severely melted due to excessive power, while ensuring a better vibration effect and improving stability and reliability.

[0052] Embodiment 2

[0053] Different from the first embodiment, the present invention provides a casting device for a bimetallic casting suitable for sand casting, referring to Figure 3 and Figure 4 As shown, it includes a mold 2, a solid inlay 3 and an ultrasonic vibration unit 1, wherein:

[0054] A cavity is formed in the casting mold 2; the casting mold 2 comprises an upper mold 201, a lower mold 202 and a pouring unit 203; the upper mold 201 and the lower mold 202 are connected to form the cavity therebetween; the pouring unit 203 is connected to the cavity; a pouring hole of the pouring unit 203 is connected to the top of the cavity, and liquid metal melt is poured in a self-pouring manner; the casting mold 2 can be used for casting of liquid magnesium and magnesium alloys, liquid aluminum and aluminum alloys, liquid copper and copper alloys, liquid steel or liquid titanium alloys;

[0055] The solid inlay 3 is pre-placed in the mold cavity; the solid inlay 3 includes an inlay body 301, an auxiliary fixing structure 302 and a temperature measuring thermocouple 303, the inlay body 301 is rigidly connected to the auxiliary fixing structure 302, the auxiliary fixing structure 302 is connected to the lower mold 202, the auxiliary fixing structure 302 can use screws, and the bottom surface of the inlay body 301 is fixed to the bottom of the lower mold 202 by screws, the four side surfaces and the top surface of the inlay body 301 are free surfaces, the temperature measuring thermocouple 303 is installed on the inlay body 301, the temperature measuring thermocouple 303 is located at the bottom of the inlay body 301 and inserted into the mold cavity; the inlay body 301 can be a solid magnesium and magnesium alloy, solid aluminum and aluminum alloy, solid copper and copper alloy, solid steel or solid titanium and titanium alloy component;

[0056] At least two ultrasonic vibration units 1 are provided, and the ultrasonic vibration units 1 include an ultrasonic generator 101 and an ultrasonic vibration mechanism. The ultrasonic generator 101 is connected to the ultrasonic vibration mechanism and is used to control the ultrasonic vibration mechanism to generate ultrasonic vibrations. The ultrasonic vibration mechanism is installed on the mold 2, and at least two ends of the ultrasonic vibration mechanism are distributed above and / or on the side of the solid inlay 3, and a gap is provided between the ends of the ultrasonic vibration mechanism and the solid inlay 3. The ends of at least two ultrasonic vibration mechanisms are distributed on at least two of the five free surfaces of the solid inlay 3.

[0057] In some embodiments, the mold 2 has a cube shape, and five ultrasonic vibration units 1 are provided, wherein four of the ultrasonic vibration units 1 are provided on four sides of the mold 2, so that the four ultrasonic vibration mechanisms are respectively located on the four sides of the solid inlay 3, and another ultrasonic vibration unit 1 is provided on the top surface of the mold 2, so that the ultrasonic vibration mechanism is located above the solid inlay 3, and ultrasonic vibration is applied to the surroundings and top surface of the solid inlay 3, thereby simultaneously improving the strength of the matrix and interface of the bimetallic casting.

[0058] In some further embodiments, the ultrasonic vibration mechanism includes a transducer 102, a horn 103 and a tool head 104; the transducer 102 is electrically connected to the ultrasonic generator 101; the two ends of the horn 103 are rigidly connected to the transducer 102 and the tool head 104 respectively; one end of the tool head 104 away from the horn 103 serves as the end of the ultrasonic vibration mechanism, and the tool head 104 is connected to the casting mold 2. Four tool heads 104 are connected to the four side surfaces of the lower mold 202 and can be flush with the inner wall of the lower mold 202, and one tool head 104 is connected to the top surface of the upper mold 201 and can be flush with the inner wall of the upper mold 201, so as to more directly transmit the ultrasonic vibration to the liquid metal melt and improve the strength of the matrix.

[0059] Embodiment 3

[0060] This embodiment provides a casting device for a bimetallic casting suitable for lost foam casting, referring to Figure 5 and Figure 6 As shown, it includes a mold 2, a solid inlay 3 and an ultrasonic vibration unit 1, wherein:

[0061] A cavity is formed in the casting mold 2; the casting mold 2 includes a pouring unit 203, a sand box 205, a foam model 204 and sand 206, the pouring unit 203 is connected to the foam model 204, the ultrasonic vibration unit 1 is arranged in the sand box 205 and connected to the side and / or top surface of the foam model 204, and the sand 206 is filled in the blank area of ​​the sand box 205; the casting mold 2 can be used for casting of liquid magnesium and magnesium alloys, liquid aluminum and aluminum alloys, liquid copper and copper alloys, liquid steel or liquid titanium alloys;

[0062] The solid inlay 3 is pre-placed in the mold cavity; the solid inlay 3 includes an inlay body 301, an auxiliary fixing structure 302 and a temperature measuring thermocouple 303, the inlay body 301 is rigidly connected to the auxiliary fixing structure 302, the auxiliary fixing structure 302 is connected to the sand box 205, the auxiliary fixing structure 302 can use screws, and the bottom surface of the inlay body 301 is fixed to the bottom of the sand box 205 by screws, the four side surfaces and the top surface of the inlay body 301 are free surfaces, the temperature measuring thermocouple 303 is installed on the inlay body 301, and the temperature measuring thermocouple 303 is located in the middle of the inlay body 301; the inlay body 301 can be a solid magnesium and magnesium alloy, solid aluminum and aluminum alloy, solid copper and copper alloy, solid steel or solid titanium and titanium alloy component;

[0063] At least two ultrasonic vibration units 1 are provided, and the ultrasonic vibration units 1 include an ultrasonic generator 101 and an ultrasonic vibration mechanism. The ultrasonic generator 101 is connected to the ultrasonic vibration mechanism and is used to control the ultrasonic vibration mechanism to generate ultrasonic vibration. The ultrasonic vibration mechanism is installed on the foam model 204, and at least two ends of the ultrasonic vibration mechanism are distributed above and / or on the side of the solid inlay 3, and a gap is provided between the ends of the ultrasonic vibration mechanism and the solid inlay 3. At least two ends of the ultrasonic vibration mechanism are distributed on at least two free surfaces of the five free surfaces of the solid inlay 3.

[0064] In some embodiments, the casting mold 2 also includes a vacuum diaphragm 208, a vacuum chamber 209 and a vibration table 207. The vacuum diaphragm 208 is covered on the top of the sand box 205, the vacuum chamber 209 is arranged at the bottom of the sand box 205 and is connected to the sand box 205, and the vacuum chamber 209 is used to connect to a vacuum pumping device; the vibration table 207 is arranged below the vacuum chamber 209 and is used to support the vacuum chamber 209 and the sand box 205.

[0065] In some embodiments, the casting mold 2 has a cube shape, and five ultrasonic vibration units 1 are provided, wherein four of the ultrasonic vibration units 1 are provided on four sides of the foam model 204, so that the four ultrasonic vibration mechanisms are respectively located on the four sides of the solid inlay 3, and another ultrasonic vibration unit 1 is provided on the top surface of the foam model 204, so that the ultrasonic vibration mechanism is located above the solid inlay 3, and ultrasonic vibration is applied to the surroundings and top surface of the solid inlay 3, thereby simultaneously improving the strength of the matrix and interface of the bimetallic casting.

[0066] In some further embodiments, the ultrasonic vibration mechanism includes a transducer 102, a horn 103 and a tool head 104; the transducer 102 is electrically connected to the ultrasonic generator 101; the two ends of the horn 103 are rigidly connected to the transducer 102 and the tool head 104 respectively; one end of the tool head 104 away from the horn 103 serves as the end of the ultrasonic vibration mechanism, and the tool head 104 is connected to the casting mold 2. Five tool heads 104 are connected to the four side surfaces and the top surface of the foam model 204, and can be flush with the inner wall of the foam model 204, so as to more directly transmit the ultrasonic vibration to the liquid metal melt and improve the strength of the matrix.

[0067] Embodiment 4

[0068] The embodiment of the present invention provides a casting method of a bimetallic casting, such as Fig. 9 As shown, the casting device using the bimetallic castings described in embodiments one, two and three comprises the following steps:

[0069] Step S1: after grinding, alkali washing and acid washing the surface of the inlay body 301 of the solid inlay 3, pouring liquid metal through the pouring unit 203 of the casting mold 2;

[0070] Step S2: when the surface temperature of the solid inlay 3 is within the range of ±50°C of the liquidus of the casting metal, at least two of the ultrasonic vibration units 1 are started to apply ultrasonic vibration for 5 to 180 seconds;

[0071] Applying ultrasonic vibration within the range of ±50°C of the magnesium alloy liquidus can effectively refine the magnesium alloy matrix structure and improve the matrix performance. By setting the above vibration time, it is avoided that the ultrasonic action time is insufficient to achieve the effect of refining the structure and breaking the interface oxide film, and the problem that the ultrasonic action time is too long, on the one hand, the thermal effect generated by the ultrasonic wave will cause the grains to grow, and on the other hand, the surface of the inlay body 301 will be excessively melted, causing the inlay body 301 to lose its original shape characteristics and fail.

[0072] Step S3: when the surface temperature of the solid inlay 3 is 0-50°C above the interface formation temperature of the bimetallic composite material, at least two of the ultrasonic vibration units 1 are started to apply ultrasonic vibration for 3-80s; the interface formation temperature corresponds to the temperature at which the intermetallic compound or eutectic structure is formed, whichever is higher, for example, the aluminum / magnesium interface formation temperature corresponds to the intermetallic compound formation temperature of 458°C, the eutectic structure formation temperature of 437°C, whichever is higher, the aluminum / magnesium bimetallic interface formation temperature is 458°C; the aluminum / steel interface corresponds to the intermetallic compound formation temperature of 1160°C, the eutectic temperature of 655°C, and the interface formation temperature of 1160°C;

[0073] Applying ultrasonic vibration within the range of 0-50°C above the interface formation temperature can promote element diffusion in the interface area, improve the uniformity of the interface structure, break the oxide film and refine the interface structure; by setting the above vibration time, it is avoided that the ultrasonic action time is insufficient to achieve the effect of refining the structure and breaking the interface oxide film, and it is avoided that the ultrasonic action time is too long, on the one hand, the thermal effect generated by the ultrasonic wave will cause the grains to grow, and on the other hand, the surface of the inlay body 301 will be excessively melted, causing the inlay body 301 to lose its original shape characteristics and fail;

[0074] Step S4: When the surface temperature of the solid inlay 3 drops to 50-200° C., the solidified casting is taken out from the pouring device to obtain a bimetallic casting.

[0075] Comparative Example 1

[0076] The casting equipment of the third embodiment is used, aluminum alloy is used as the inlay body 301, and liquid magnesium alloy is used as the pouring metal liquid to prepare magnesium / aluminum bimetallic, but ultrasound is not turned on. The casting method of the bimetallic casting includes the following steps:

[0077] (1) Assemble the aluminum alloy inlay body 301, the temperature measuring thermocouple 303 and the foam model 204 and place them in the sand box 205 for fixing. After installing and adjusting the ultrasonic vibration mechanism, vibrate and fill the sand until the sand box 205 is filled. Place a vacuum diaphragm 208 on the top of the sand 206 and then evacuate the sand box;

[0078] (2) placing a pouring cup on the top of the pouring unit 203 of the foam model 204, and then pouring the liquid magnesium alloy into the pouring cup;

[0079] (3) When the temperature measured by the temperature measuring thermocouple 303 drops to 50-200 °C, the solidified casting is taken out and the pouring unit 203 is removed to obtain a magnesium / aluminum bimetallic casting.

[0080] In this embodiment, in step (1), the angle between the axis of the ultrasonic vibration mechanism and the surface of the aluminum alloy solid inlay 3 is 90°, the distance between the end face of the ultrasonic vibration mechanism and the surface of the aluminum alloy solid inlay 3 is 40 mm, the vacuum degree in the sand box 205 reaches 0.01-0.05 MPa, and the pouring temperature of the magnesium alloy in step (2) is 730°C.

[0081] Application Example 1

[0082] The casting device of the third embodiment is used, aluminum alloy is used as the inlay body 301, and liquid magnesium alloy is used as the casting metal liquid to prepare magnesium / aluminum bimetal. The casting method of the bimetal casting includes the following steps:

[0083] (1) Assemble the aluminum alloy inlay body 301, the temperature measuring thermocouple 303 and the foam model 204 and place them in the sand box 205 for fixing. After installing and adjusting the ultrasonic vibration mechanism, vibrate and fill the sand until the sand box 205 is filled. Place a vacuum diaphragm 208 on the top of the sand 206 and then evacuate the sand box;

[0084] (2) placing a pouring cup on the top of the pouring unit 203 of the foam model 204, and then pouring the liquid magnesium alloy into the pouring cup;

[0085] (3) when the temperature measured by the thermocouple 303 is ±50°C above the liquidus of the magnesium alloy and 0 to 50°C above the magnesium-aluminum interface formation temperature, the ultrasonic generator 101 is started;

[0086] (4) when the temperature measured by the temperature measuring thermocouple 303 is 0 to 50° C. above the magnesium-aluminum interface formation temperature, the ultrasonic generator 101 is started;

[0087] (5) When the temperature measured by the temperature measuring thermocouple 303 drops to 50-200 °C, the solidified casting is taken out and the pouring unit 203 is removed to obtain a magnesium / aluminum bimetallic casting.

[0088] In this embodiment, in step (1), the angle between the axis of the ultrasonic vibration mechanism and the surface of the aluminum alloy solid inlay 3 is 90°, the distance between the end face of the ultrasonic vibration mechanism and the surface of the aluminum alloy solid inlay 3 is 40 mm, the vacuum degree in the sand box 205 reaches 0.01-0.05 MPa, the pouring temperature of the magnesium alloy in step (2) is 730°C, and in step (3), the ultrasonic generator is turned on at 580°C and 475°C for 1015s, the frequency of the ultrasonic generator 101 is 20kHz, and the power is 500W, to obtain an aluminum / magnesium bimetallic casting.

[0089] Applying ultrasonic vibration within the range of ±50°C of the magnesium alloy liquidus can effectively refine the magnesium alloy matrix structure and improve the matrix performance. 580°C is selected in this embodiment; applying ultrasonic vibration within the range of 0~50°C above the interface formation temperature can promote the diffusion of elements in the interface area, improve the uniformity of the interface structure, break up the oxide film and refine the interface structure.

[0090] SEM Testing

[0091] Figure 7 The SEM test images of the magnesium alloy substrates of Application Example 1 and Comparative Example 1 are shown in FIG. Figure 7 (a1) is a test diagram of the magnesium alloy matrix structure of Comparative Example 1, wherein Figure 7 (b1) in FIG. 1 is a test diagram of the magnesium alloy matrix structure of Application Example 1. Figure 7 It can be seen that the precipitated phase in the matrix is ​​refined and dispersed after the application of ultrasonic vibration, and the distribution is more uniform.

[0092] EBSD testing

[0093] Figure 8 EBSD test images of the magnesium-aluminum interface of Application Example 1 and Comparative Example 1, wherein Figure 8 (a2) is a test diagram of the interface structure of Comparative Example 1, where Figure 8 (b2) in FIG. 1 is a test diagram of the interface organization of the application example 1. Figure 8 It can be seen that the interface grains are significantly refined after the application of ultrasonic vibration.

[0094] Application Example 2

[0095] The frequency of the ultrasonic generator 101 is 12 kHz, the power is 500 W, and the other parameters are the same as those in Application Example 1.

[0096] Application Example 3

[0097] The frequency of the ultrasonic generator 101 is 28 kHz, the power is 500 W, and the other parameters are the same as those in Application Example 1.

[0098] Application Example 4

[0099] The ultrasonic generator 101 has a frequency of 20 kHz and a power of 50 W. Other parameters are the same as those in Application Example 1.

[0100] Application Example 5

[0101] The frequency of the ultrasonic generator 101 is 20 kHz, the power is 200 W, and the other parameters are the same as those in Application Example 1.

[0102] Comparative Example 2

[0103] Steel is used as the inlay body 301 and liquid aluminum alloy is used as the casting metal liquid to prepare aluminum / steel bimetal. No ultrasonic wave is applied and other parameters are the same as those in comparative example 1.

[0104] Application Example 6

[0105] The ultrasonic generator 101 has a frequency of 20 kHz and a power of 2500 W. Steel is used as the inlay body 301 and liquid aluminum is used as the casting metal liquid to prepare the aluminum / steel bimetal. Other parameters are the same as those in Application Example 1.

[0106] Application Example 7

[0107] The ultrasonic generator 101 has a frequency of 20 kHz and a power of 5000 W. Steel is used as the inlay body 301 and liquid aluminum is used as the casting metal liquid to prepare the aluminum / steel bimetal. Other parameters are the same as those in Application Example 1.

[0108] Table 1 shows the test results of the shear performance of the magnesium / aluminum and aluminum / steel bimetallic interfaces of Comparative Example 1 and various application examples.

[0109]

[0110] Table 1

[0111] As shown in Table 1, after applying ultrasonic vibration, the average shear strength of the magnesium / aluminum bimetallic interface increased from 35.4MPa without ultrasonic vibration to 62.2MPa, an increase of 75.7%. After applying ultrasonic vibration, the shear strength of the aluminum / steel bimetallic interface increased from 12.8MPa without ultrasonic vibration to 87.9MPa, an increase of 600.8%.

[0112] In summary, the casting method of a bimetallic casting provided by the present invention can realize the direct action of ultrasound on the liquid metal matrix and indirectly act on the bimetallic interface. Through the cavitation effect and acoustic streaming effect of ultrasound, the matrix and interface structure of the composite casting bimetallic casting are improved at the same time, thereby improving the mechanical properties of the bimetallic casting.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A casting method for a bimetallic casting, using a casting device for a bimetallic casting, characterized in that: The casting device comprises a casting mold, a solid inlay and an ultrasonic vibration unit; a cavity is formed in the casting mold; the solid inlay is pre-placed in the cavity; at least two ultrasonic vibration units are provided, and the ultrasonic vibration units include an ultrasonic generator and an ultrasonic vibration mechanism, the ultrasonic generator is connected to the ultrasonic vibration mechanism, and is used to control the ultrasonic vibration mechanism to generate ultrasonic vibration; the ultrasonic vibration mechanism is installed on the casting mold, and ends of at least two of the ultrasonic vibration mechanisms are distributed above, below and / or on the side of the solid inlay, and a gap is provided between the ends of the ultrasonic vibration mechanism and the solid inlay; The casting method comprises: After grinding, alkali washing and pickling treatment on the surface of the inlay body of the solid inlay, pouring liquid metal through the pouring unit of the casting mold; When the surface temperature of the solid inlay is within the range of ±50°C of the liquidus of the casting metal, at least two of the ultrasonic vibration units are started to apply ultrasonic vibration for 5 to 180 seconds; When the surface temperature of the solid inlay is 0 to 50° C. above the interface formation temperature of the bimetallic composite material, at least two of the ultrasonic vibration units are activated to apply ultrasonic vibration for 3 to 80 seconds; When the surface temperature of the solid inlay drops to 50-200° C., the solidified casting is taken out from the pouring device to obtain a bimetallic casting.

2. The casting method of a bimetallic casting according to claim 1, characterized in that: The mold has a cube shape, and five ultrasonic vibration units are provided, wherein four of the ultrasonic vibration units are provided on four side surfaces of the mold, and another ultrasonic vibration unit is provided on the top surface or the bottom surface of the mold.

3. The casting method of a bimetallic casting according to claim 1, characterized in that: The ultrasonic vibration mechanism includes a transducer, a horn and a tool head; the transducer is electrically connected to the ultrasonic generator; the two ends of the horn are rigidly connected to the transducer and the tool head respectively; the end of the tool head away from the horn serves as the end of the ultrasonic vibration mechanism, and the tool head is connected to the casting mold.

4. The casting method of a bimetallic casting according to claim 3, characterized in that: The ultrasonic vibration unit is in a resonant state when working, and the resonant frequency of the transducer is 12~28kHz.

5. The casting method of a bimetallic casting according to claim 3, characterized in that: When the liquid phase difference between the liquid metal melt and the solid inlay used for casting is less than or equal to 200°C, the power of the ultrasonic generator is 50-500W; when the liquid phase difference is greater than or equal to 200°C, the power of the ultrasonic generator is 500-5000W.

6. The casting method of a bimetallic casting according to claim 1, characterized in that: The casting mold comprises an upper mold, a lower mold and a pouring unit. The upper mold and the lower mold are connected to form the mold cavity therebetween. The pouring unit is in communication with the mold cavity.

7. The casting method of a bimetallic casting according to claim 6, characterized in that: The solid inlay comprises an inlay body, an auxiliary fixing structure and a temperature measuring thermocouple, the inlay body is rigidly connected to the auxiliary fixing structure, the auxiliary fixing structure is connected to the upper mold or the lower mold, and the temperature measuring thermocouple is installed on the inlay body.

8. The casting method of a bimetallic casting according to claim 1, characterized in that: If the casting device uses lost foam casting, the mold includes a pouring unit, a sand box, a foam model and sand, the pouring unit is connected to the foam model, the solid inlay is installed at the bottom of the sand box, the ultrasonic vibration unit is arranged in the sand box and connected to the side and / or top surface of the foam model, and the sand is filled in the blank area of ​​the sand box.

9. The casting method of a bimetallic casting according to claim 8, characterized in that: The casting mold further comprises a vacuum diaphragm and a vacuum chamber, wherein the vacuum diaphragm cover is arranged on the top of the sand box, the vacuum chamber is arranged on the bottom of the sand box and communicated with the sand box, and the vacuum chamber is used to be connected to a vacuum pumping device.

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