A semi-solid pulping device and method combining mechanical agitation and heat balance control

Abstract

A kind of semi-solid slurry device of mechanical stirring and heat balance control combination, comprising: a mechanical stirring rod the shape of J type stirring rod of letter "J" and its matched dry ice cooling cleaning device, the curved end of the J type stirring rod is inserted into metal melt, the mechanical stirring range of stirring rod is expanded, while the stirring speed is reduced, to avoid the vortex of metal melt surface generated by stirring or reduce the diameter range of stirring vortex;The method for preparing semi-solid slurry using the device is to use J type stirring rod to mechanically stir metal melt, and use dry ice to clean the metal oxide surface residue adhered to J type stirring rod after stirring metal melt, to avoid metal oxide residue entering next metal melt with stirring rod again;The above device and method can prepare high-melt-quality metal semi-solid slurry with low cost and high efficiency, and can ensure the continuity, stability and consistency of metal semi-solid slurry preparation in industrial production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal semi-solid slurry processing, and particularly relates to a mechanical stirring and heat balance control combined semi-solid slurry preparation device and a slurry preparation method using the same. BACKGROUND

[0002] In the existing metal semi-solid slurry preparation process, a mechanical stirring type slurry preparation method can break the dendritic structure of the metal melt growing in the solidification process to form a rosette or spherical structure, and is a commonly used method for preparing metal semi-solid slurry. However, the defects caused by the mechanical stirring often lead to that the quality of the semi-solid slurry cannot meet the requirements. On the one hand, the vortex of the metal melt generated by high-speed stirring can roll the impurities such as oxidation slag on the surface of the metal melt into the metal melt; on the other hand, the metal oxide scale adhered to the inserted stirring rod is stirred into the metal melt again. The existence and uneven distribution of the rolled-in metal oxide impurities in the prepared metal slurry are the reasons for the poor consistency of the metal semi-solid slurry prepared by the traditional mechanical stirring semi-solid slurry preparation method, so the excellent performance advantages of the metal semi-solid forming cannot be fully played.

[0003] For example, the SSR semi-solid slurry preparation technology invented by Massachusetts Institute of Technology uses a straight rod type graphite rod to stir the metal melt, which can only achieve the effect of mechanical stirring within a certain diameter range, and the high-speed stirring of the stirring rod and the adhered metal oxide will pollute the quality of the metal melt. For example, the gas-cooled stirring semi-solid slurry preparation technology invented by Beijing University of Science and Technology uses a stirring rod that can be cooled by circulating gas inside to stir and prepare the metal melt, which also cannot avoid the influence of the above-mentioned stirring rolled-in oxidation inclusions on the quality of the metal melt. In the above patents, the mechanical stirring is the traditional mechanical stirring using a straight rod type stirring rod. In order to achieve the effect of mechanical stirring and increase the stirring diameter range, the stirring speed is usually increased, and with the increase of the stirring speed, the vortex diameter and depth generated by the stirring will increase, which will lead to that the metal oxide on the surface of the melt in contact with the air will be rolled into the metal melt by several times. Therefore, how to avoid the rolling-in of the metal oxide in the mechanical stirring slurry preparation method is the key to the wide application of the mechanical stirring slurry preparation process in production.

[0004] In addition, with the rise and development of new fields such as integrated die casting, the weight and size of the single metal semi-solid slurry prepared by the metal semi-solid forming are required to be larger. This also exposes that the mechanical stirring method cannot uniformly stir the metal melt or even cannot stir part of the metal melt due to the limitation of the stirring diameter range. Meanwhile, the thermal balance state of the metal melt at the edge and the center of the larger size metal melt is inconsistent due to the limitation of the stirring range, which is one of the reasons for the poor consistency of the metal semi-solid slurry. Therefore, it is necessary to increase the stirring range and control the thermal balance of the edge and the center of the metal melt, which is the solution to ensure the internal consistency of the metal semi-solid slurry. SUMMARY

[0005] In order to overcome the above problems of the prior art, one of the purposes of the present application is to provide a slurry preparation device for reducing the involvement of metal oxide defects in the preparation of metal semi-solid slurry by mechanical stirring and improving the quality of metal semi-solid slurry.

[0006] The second purpose of the present application is to provide a slurry preparation method for effectively improving and controlling the preparation of large size slurry and the overall uniformity and consistency of the thermal balance of the metal semi-solid slurry by using the slurry preparation device of the present application.

[0007] Specifically, the first aspect of the present application provides a semi-solid slurry preparation device combined with mechanical stirring and thermal balance control, comprising: a J-shaped stirring rod 101 in the shape of a letter "J" of a mechanical stirring rod and a dry ice cooling and cleaning device 3 matched therewith, and the curved end of the J-shaped stirring rod 101 is inserted into the metal melt 4. The mechanical stirring range of the stirring rod is expanded, and the stirring speed is reduced to avoid or reduce the diameter range of the vortex on the surface of the metal melt.

[0008] In the semi-solid slurry preparation device of the present application, the bending arc of the J-shaped bending part of the J-shaped stirring rod 101 is less than 90 degrees, and an anti-sticking coating is sprayed on the surface of the stirring rod.

[0009] In the semi-solid slurry preparation device of the present application, the J-shaped stirring rod 101 is made of stainless steel, the diameter of the stirring rod is 20-100 mm, the wall thickness of the stirring rod is 10-50 mm, the bending radius of the stirring rod is 50-200 mm, the length of the stirring rod is 200-800 mm, and a 1-2 mm anti-sticking ceramic coating is sprayed on the surface of the stirring rod.

[0010] In the semi-solid slurry preparation device, after the J-shaped stirring rod 101 completes stirring and is pulled out from the metal melt 4, the curved end of the J-shaped stirring rod 101 inserted into the metal melt is sprayed at high speed by compressed air driving dry ice, the J-shaped stirring rod 101 is cooled to the initial temperature by sublimation of the dry ice, and the metal melt and its oxides adhered to the J-shaped stirring rod 101 are removed by high-speed blasting of the dry ice.

[0011] In the semi-solid slurry preparation device, the stirring rod 101 is embedded with a thermocouple 202 and a temperature measuring instrument 203, and the metal melt 4 temperature measuring thermocouple 201 and temperature measuring instrument 203 monitor the temperature of the metal melt 4 in real time.

[0012] The second aspect of the application is to provide a semi-solid slurry preparation method using the semi-solid slurry preparation device of the first aspect of the application, which uses the J-shaped stirring rod 101 inserted into the metal melt 4 to absorb the heat of the center of the metal melt 4 by the J-shaped stirring rod 101 itself, and to keep the thermal balance consistency of each region of the metal melt 4 by the wider stirring range of the J-shaped stirring rod 101; the metal melt 4 organization is refined to a spherical shape by the shearing action between the mechanical stirring of the J-shaped stirring rod 101 and the metal melt; the initial temperature of the J-shaped stirring rod before stirring is stable and consistent by the matched dry ice cooling and cleaning method, and the formation of the entrapment type defects of the metal melt is avoided or reduced.

[0013] The semi-solid slurry preparation method includes the following specific steps:

[0014] 1) After the ceramic ladle 402 holds a certain mass of metal melt 4, the J-shaped stirring rod 101 is lowered from above the metal melt 4 and along the center of the metal melt 4 to the curved part of the J-shaped stirring rod 101, and the J-shaped stirring rod 101 is inserted into the metal melt 4; the J-shaped stirring rod 101 with a fixed mass and an initial temperature is inserted into the metal melt 4 to absorb the corresponding heat of the metal melt 4, and at the same time, the temperature of the center of the metal melt 4 in contact with the J-shaped stirring rod 101 is reduced;

[0015] 2) The J-shaped stirring rod 101 is driven by the pre-set speed of the driving motor 102 to mechanically stir the metal melt 4, so that the temperature of each region of the metal melt 4 is uniform, the consistency control of the overall thermal balance of the metal melt 4 in the cooling process is achieved, and the uniform nucleation of the metal melt 4 in the solidification process is promoted; at the same time, the shearing action of the J-shaped stirring rod 101 on the metal melt 4 breaks the organization of the metal melt 4 that has been nucleated in the solidification process and avoids further growth, so as to achieve a refined spherical or rosette-shaped aluminum alloy semi-solid slurry organization;

[0016] 3) When the metal melt temperature measuring thermocouple 201 and the temperature measuring instrument 203 monitor the temperature of the metal melt 4 in real time and reach the pre-set temperature, the J-shaped stirring rod 101 stops stirring and is pulled out from the metal melt 4.

[0017] 4) The dry ice spray gun 301 of the dry ice cleaning and cooling system (3) sprays dry ice to the surface of the J-shaped stirring rod 101, and the heat of the J-shaped stirring rod 101 is taken away by the sublimation of the dry ice, so that the J-shaped stirring rod 101 is cooled to the initial state.

[0018] In the method of the application, the metal melt 4 and its oxides adhered to the J-shaped stirring rod 101 are removed by the high-speed blasting of the dry ice, so that the metal oxides are prevented from entering the next metal melt 4 again with the stirring rod, and the semi-solid slurry preparation effect is ensured.

[0019] The application has the following beneficial effects:

[0020] The device and method of the application can greatly avoid the generation of oxide inclusion defects in the process of metal semi-solid slurry preparation, and can expand the size and weight range of semi-solid slurry preparation. In actual application, the device has simple mechanical structure, reliable and controllable process, and high consistency of the prepared metal semi-solid slurry. Therefore, in industrialized scale production, the device can reduce the equipment investment cost and technical upgrading difficulty of existing production enterprises, maintain the stability and consistency of product quality under the premise of low-cost application, and is very beneficial to the popularization and application of the application technology in related metal processing enterprises, and can effectively improve the production efficiency, reduce the production cost, and lay a reliable technical foundation for manufacturing high-quality products. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the overall structure diagram of the mechanical stirring and heat balance control combined semi-solid slurry preparation device of the application.

[0022] Figure 2 is a schematic diagram of cleaning and cooling of the J-shaped stirring rod.

[0023] The following table explains the reference signs: J-shaped stirring rod system 1, J-shaped stirring rod 101, driving motor 102, frequency converter 103, temperature measurement system 2, metal melt temperature measurement thermocouple 201, stirring rod embedded thermocouple 202, temperature measurement instrument 203, surface temperature measurement infrared thermometer 204, dry ice cleaning and cooling system 3, dry ice spray gun 301, dry ice pipeline 302, compressed air pipeline 303, metal melt 4, aluminum alloy liquid 401, ceramic ladle 402.

[0024] Figure 3 is the aluminum alloy semi-solid slurry metallographic microstructure in the embodiments 1 and 2 of the application.

[0025] Figure 4 is the aluminum alloy semi-solid slurry metallographic microstructure in the embodiment 3 of the application. DETAILED DESCRIPTION

[0026] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clear, specific embodiments will be described in detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. Example 1

[0027] Reference Figure 1 and Figure 2 As shown in FIG. 1, a mechanical stirring and heat balance control combined semi-solid slurry preparation device mainly comprises a J-shaped stirring rod system 1, a temperature measuring system 2, a dry ice cleaning and cooling system 3 and a metal melt 4. The J-shaped stirring rod system 1 comprises a J-shaped stirring rod 101, a driving motor 102 and a frequency converter 103; the temperature measuring system 2 comprises a metal melt temperature measuring thermocouple 201, a stirring rod embedded thermocouple 202 and a temperature measuring instrument 203; the dry ice cleaning system 3 comprises a dry ice spray gun 301, a dry ice pipeline 302 and a compressed air pipeline 303; and the metal melt 4 is an aluminum alloy liquid 401 with a weight of 5-10 kg, which is contained by a ceramic ladle 402.

[0028] The J-shaped stirring rod 101 is made of stainless steel, with a diameter of 20-10 mm, a wall thickness of 10-50 mm, a bending radius of 50-200 mm, a length of 200-800 mm, and a surface thermal spraying of a 1-2 mm anti-sticking ceramic coating.

[0029] The driving motor 102 is connected to the J-shaped stirring rod 101, and the frequency converter 103 outputs different frequencies to control the rotating speed of the driving motor 102, so as to adjust and control the stirring speed of the J-shaped stirring rod 101.

[0030] The stirring rod 101 is embedded with the thermocouple 202 and the temperature measuring instrument 203, which are used to monitor the temperature of the J-shaped stirring rod 101 in the stirring process of inserting into the aluminum alloy liquid 401 and the cleaning and cooling process of the J-shaped stirring rod 101 by the dry ice cleaning and cooling system 3; and the metal melt temperature measuring thermocouple 201 and the temperature measuring instrument 203 are used to monitor the temperature of the aluminum alloy liquid 401.

[0031] The dry ice cleaning system 3, such as Figure 2As shown, dry ice particles in dry ice pipe 302 are driven by dry, clean compressed air in compressed air pipe 303 and ejected at high speed from dry ice spray gun 301. The ejected dry ice particles shatter and sublime upon impacting the surface of J-shaped stirring rod 101. The explosive energy generated by the shattering dry ice breaks up the aluminum alloy scale adhering to the surface of J-shaped stirring rod 101 and removes it from the rod. Simultaneously, the sublimation of the dry ice absorbs heat from J-shaped stirring rod 101, lowering its temperature.

[0032] The process of the semi-solid slurrying method combined with mechanical stirring and heat balance control is as follows: after a certain mass of aluminum alloy liquid 401 is taken by a ceramic scoop 402, a J-shaped stirring rod 101 of a proportionally corresponding size is lowered from above the aluminum alloy liquid 401 and along the center of the aluminum alloy liquid 401 to the curved part of the J-shaped stirring rod 101 and penetrates into the aluminum alloy liquid 401. The J-shaped stirring rod 101 of a fixed mass and initial temperature is inserted into the aluminum alloy liquid 401 to absorb the corresponding heat of the aluminum alloy liquid 401, while the center of the aluminum alloy liquid 401 in contact with the J-shaped stirring rod 101 is heated. The temperature is lowered, and the J-shaped stirring rod 101 is driven by the drive motor 102 with a preset speed to mechanically stir the aluminum alloy liquid 401, so that the temperature of each area of ​​the aluminum alloy liquid 401 is uniform, thereby achieving consistent control of the overall thermal balance of the aluminum alloy liquid 401 during the cooling process, and promoting uniform nucleation of the aluminum alloy liquid 401 during the solidification process; at the same time, the shearing effect of the J-shaped stirring rod 101 on the aluminum alloy liquid 401 during mechanical stirring is used to break the nucleated structure of the aluminum alloy liquid 401 during the solidification process and prevent it from growing further, thereby achieving a refined spherical or rose-shaped aluminum alloy semi-solid slurry structure, such as Figure 3 As shown. When the temperature of the aluminum alloy liquid 401 reaches a preset temperature, as monitored in real time by the metal melt temperature measuring thermocouple 201 and the temperature measuring instrument 203, the J-shaped stirring rod 101 completes stirring and is removed from the aluminum alloy liquid 401. The J-shaped stirring rod 101 is subjected to a rotational spraying operation using the matching dry ice cooling and cleaning device 3. The dry ice in contact with the surface of the J-shaped stirring rod 101 sublimates and removes the heat from the J-shaped stirring rod 101. The stirring rod is embedded with a thermocouple 202 and a temperature measuring instrument 203 to monitor the temperature of the J-shaped stirring rod 101 in real time during the stirring process of the aluminum alloy liquid 401 and during the cleaning and cooling process of the J-shaped stirring rod 101 by the dry ice cleaning and cooling system 3, ensuring that the J-shaped stirring rod 101 is cooled to its initial temperature before stirring.

[0033] During the dry ice blasting process, the dry ice blasts and cleans the aluminum alloy oxide scale adhered to the surface of the J-shaped stirring rod 101, thereby avoiding the occurrence of aluminum alloy oxide inclusion defects. Example 2

[0034] Different from the embodiment 1, the J-shaped stirring rod 101 is a solid structure and is made of titanium alloy;Figure 2 As shown, the temperature measuring system 2 is an infrared thermometer 204 for measuring the temperature of the surface of the J-shaped stirring rod 101.

[0035] The mechanical stirring and thermal balance control combined semi-solid slurry preparation method has the following process: after the ceramic ladle 402 scoops a certain mass of aluminum alloy liquid 401, a J-shaped stirring rod 101 with a corresponding size according to the proportion is lowered from above the aluminum alloy liquid 401 and along the center position of the aluminum alloy liquid 401 to the bending part of the J-shaped stirring rod 101, which is deep into the aluminum alloy liquid 401. The J-shaped stirring rod 101 with a fixed mass and initial temperature is used to absorb the corresponding heat of the aluminum alloy liquid 401 while reducing the temperature of the core of the aluminum alloy liquid 401 in contact with the J-shaped stirring rod 101. Then, the driving motor 102 with a preset rotating speed drives the J-shaped stirring rod 101 to mechanically stir the aluminum alloy liquid 401, so that the temperature of each region of the aluminum alloy liquid 401 is uniform, achieving the consistency control of the overall thermal balance of the aluminum alloy liquid 401 in the cooling process and promoting the uniform nucleation of the aluminum alloy liquid 401 in the solidification process. At the same time, the shearing action of mechanical stirring on the aluminum alloy liquid 401 breaks the nucleated structure in the solidification process of the aluminum alloy liquid 401 and avoids further growth, achieving a refined spherical or rosette-shaped aluminum alloy semi-solid slurry structure, as shown in FIG. 4. Figure 3 After the process time required by the above stirring process is verified by experiments, the slurry preparation process is controlled by time under the premise that the initial temperature and weight of the aluminum alloy liquid 401 remain unchanged. Specifically, when the frequency converter 103 counts the preset stirring time, the driving motor 102 slows down to end the stirring of the J-shaped stirring rod 101, and the J-shaped stirring rod 101 is taken out of the aluminum alloy liquid 401. The dry ice cooling and cleaning device 3 is used to rotate and spray the J-shaped stirring rod 101. The dry ice in contact with the surface of the J-shaped stirring rod 101 sublimates and takes away the heat of the J-shaped stirring rod 101. The infrared thermometer 204 for surface temperature measurement is used to monitor the temperature of the J-shaped stirring rod after the J-shaped stirring rod 101 is cleaned and cooled by the dry ice cleaning and cooling system 3, so as to ensure that the J-shaped stirring rod 101 is cooled to the initial temperature before stirring. Example 3

[0036] Different from the implementation cases 1 and 2, the aluminum alloy liquid 401 in the implementation case 3 needs to be further refined.

[0037] The grain refining particles for the aluminum alloy liquid 401 are automatically put into the aluminum alloy liquid 401 before the J-shaped stirring rod 101 is inserted into the aluminum alloy liquid 401, and then the J-shaped stirring rod 101 mechanically stirs the aluminum alloy liquid 401 with the grain refining particles, and the grain refining particles are uniformly distributed in the aluminum alloy liquid 401 through stirring diffusion, so that more grain nucleation points are formed in the aluminum alloy liquid 401 during solidification, and the semi-solid structure of the aluminum alloy slurry is further refined and spheroidized in the process of semi-solid slurry of the aluminum alloy liquid 401 by the J-shaped stirring rod 101, as shown in Figure 4

[0038] The preferred embodiments of the present application are described above with reference to the accompanying drawings, and are not intended to limit the scope of the present application. Any modification, equivalent replacement and improvement made by those skilled in the art without departing from the scope and essence described in the claims of the present application shall be within the scope of the present application.​

Claims

1. A semi-solid slurry preparation device combining mechanical agitation and heat balance control, characterized by, It comprises: A J-shaped stirring rod (101) with a mechanical stirring rod and a dry ice cooling cleaning device (3) matched therewith, the curved end of the J-shaped stirring rod (101) is inserted into the metal melt (4), the mechanical stirring range of the stirring rod is expanded, the stirring speed is reduced, and the vortex on the surface of the metal melt is avoided or the diameter range of the stirring vortex is reduced; after the J-shaped stirring rod (101) completes stirring each time and is pulled out from the metal melt (4), the curved end of the J-shaped stirring rod (101) inserted into the metal melt is sprayed at high speed by dry ice driven by compressed air, the J-shaped stirring rod (101) is cooled to the initial temperature by sublimation of the dry ice, and the metal melt and its oxides adhered to the J-shaped stirring rod (101) are removed by the high-speed blasting of the dry ice.

2. The semi-solid pulping apparatus of claim 1, wherein, The bending arc of the J-shaped bending part of the J-shaped stirring rod (101) is less than 90 degrees, and an anti-sticking coating is sprayed on the surface of the stirring rod.

3. The semi-solid pulping apparatus of claim 2, wherein, The J-shaped stirring rod (101) is made of stainless steel, the diameter of the stirring rod is 20-100 mm, the wall thickness of the stirring rod is 10-50 mm, the bending radius of the stirring rod is 50-200 mm, the length of the stirring rod is 200-800 mm, and a 1-2 mm anti-sticking ceramic coating is thermal sprayed on the surface of the stirring rod.

4. The semi-solid pulping apparatus of claim 1, wherein, The J-shaped stirring rod (101) is embedded with a thermocouple (202) and a temperature measuring instrument (203), and the temperature measuring thermocouple (201) and the temperature measuring instrument (203) of the metal melt (4) monitor the temperature of the aluminum alloy liquid (401) in real time.

5. A semi-solid slurry preparation method using the semi-solid slurry preparation device of any one of claims 1-4, which uses the J-shaped stirring rod (101) to extend into the metal melt (4), absorbs the heat in the center of the metal melt (4) by the J-shaped stirring rod (101) itself, and maintains the thermal balance consistency of each region of the metal melt (4) by the wider stirring range of the J-shaped stirring rod (101); the metal melt (4) is refined to a spherical shape by the shearing action between the mechanical stirring of the J-shaped stirring rod (101) and the metal melt; and the initial temperature of the J-shaped stirring rod before stirring is stabilized and consistent by the matched dry ice cooling cleaning method, and the generation of the entrapment type defects of the metal melt is avoided or reduced.

6. The semi-solid slurry preparation method according to claim 5, which comprises the following steps: 1) After the ceramic ladle (402) holds a certain mass of aluminum alloy liquid (401), the J-shaped stirring rod (101) is lowered from above the aluminum alloy liquid (401) and along the center position of the aluminum alloy liquid (401) to the curved part of the J-shaped stirring rod (101) to extend into the aluminum alloy liquid (401); the J-shaped stirring rod (101) with a fixed mass and initial temperature is used to extend into the aluminum alloy liquid (401) to absorb the corresponding heat of the aluminum alloy liquid (401) while reducing the temperature of the center of the aluminum alloy liquid (401) in contact with the J-shaped stirring rod (101). 2) The J-shaped stirring rod (101) is driven by the preset rotating speed of the driving motor (102) to mechanically stir the aluminum alloy liquid (401), so that the temperature of each region of the aluminum alloy liquid (401) is uniform, the consistency control of the overall thermal balance of the aluminum alloy liquid (401) in the cooling process is achieved, and the uniform nucleation of the aluminum alloy liquid (401) in the solidification process is promoted; at the same time, the shearing action of the J-shaped stirring rod (101) on the aluminum alloy liquid (401) breaks the nucleated structure in the solidification process of the aluminum alloy liquid (401) and avoids further growth, so that the refined spherical or rosette-shaped aluminum alloy semi-solid slurry structure is achieved; 3) When the temperature of the aluminum alloy liquid (401) monitored by the metal melt temperature measuring thermocouple (201) and the temperature measuring instrument (203) reaches the preset temperature, the J-shaped stirring rod (101) stops stirring and is withdrawn from the aluminum alloy liquid (401); 4) The dry ice spray gun (301) of the dry ice cooling and cleaning device (3) sprays dry ice onto the surface of the J-shaped stirring rod (101), and the heat of the J-shaped stirring rod (101) is taken away by the sublimation of the dry ice, so that the J-shaped stirring rod (101) is cooled to the initial state.

7. The semi-solid slurry preparation method of claim 6, wherein the metal melt and its oxides adhering to the J-shaped stirring rod (101) are removed by high-speed blasting of dry ice, so that the metal oxides are prevented from being left in the metal melt again with the J-shaped stirring rod (101) in the next time, and the high-quality semi-solid slurry effect is ensured.

Images