Device and method for rapidly preparing semi-solid metal slurry

Abstract

The present invention relates to a device and method for rapidly preparing semi-solid metal slurry, which comprises a container for placing metal slurry, a permanent magnetic stirring mechanism for driving electromagnetic stirring of the metal slurry in the container, and a cooling mechanism for cooling the metal slurry. The purpose of the present invention is to provide a device for rapidly preparing semi-solid metal slurry, which can make the metal slurry evenly and fully cooled and stirred, and prepare high-quality semi-solid metal slurry. The advantages of the present invention are: using permanent magnets to generate magnetic force for non-contact stirring, saving energy and cost, making the metal slurry free from pollution, and stirring without dead angles.

Description

Technical Field

[0001] The invention relates to a device and a method for rapidly preparing semi-solid metal slurry. Background Art

[0002] Semi-solid slurrying technology refers to the process of vigorously stirring the metal during the solidification process to control the solid-liquid temperature range to obtain a solid-liquid mixed slurry in which a certain solid phase component is evenly suspended in the liquid metal mother liquor (the solid phase component can even be as high as 60%). This semi-solid metal slurry has rheological properties, that is, it has good fluidity and can be easily made into complex products through ordinary casting methods.

[0003] Since the semi-solid forming technology was proposed by MIT in the 1970s, semi-solid slurrying technology has been the focus of research and development, and has also developed rapidly in recent years. The purpose of slurrying is to break up the dendrites or faceted crystal morphology, obtain spherulites, and control the crystal growth during the cooling and solidification process, so as to obtain alloy slurry with good rheological properties. Semi-solid forming technology breaks the traditional dendrite solidification mode, makes the alloy structure uniform, reduces the internal defects of the casting, improves the comprehensive performance of the casting, and under the same requirements, can also appropriately reduce the wall thickness of the casting, thereby reducing the weight of the casting.

[0004] At present, there are many devices and processes for preparing semi-solid slurries, such as mechanical stirring, electromagnetic stirring, ultrasonic stirring, controlled solidification, strain activation, and powder metallurgy. However, these existing semi-solid slurry preparation devices and methods have problems such as low efficiency, high cost, and difficulty in controlling the solid phase ratio, making it difficult to achieve large-scale industrial production of semi-solid forming technology. Summary of the invention

[0005] The object of the present invention is to provide a device and method for quickly preparing semi-solid metal slurry, which can make the metal slurry evenly and fully cooled and stirred, and prepare high-quality semi-solid metal slurry.

[0006] The objective of the present invention is achieved through the following technical scheme: a device for rapidly preparing semi-solid metal slurry, comprising a container for placing metal slurry, a permanent magnetic stirring mechanism for driving electromagnetic stirring of the metal slurry in the container, and a cooling mechanism for cooling the metal slurry; the cooling mechanism comprises a coolant delivery core and a conductive seal, the coolant delivery core is vertically arranged, and the outer peripheral wall of the lower section thereof is provided with an annular cooling groove, the conductive seal is sleeved at the lower section of the coolant delivery core, and the inner wall thereof and the annular cooling groove form a cooling channel, and the coolant delivery core is also provided with a liquid inlet channel and a liquid outlet channel connected to the cooling channel; the conductive seal is located inside the cavity of the container, and the outer peripheral wall of the conductive seal is provided with a plurality of vertically extending arc-shaped spoiler grooves, and the arc-shaped spoiler grooves are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center.

[0007] Compared with the prior art, the advantages of the present invention are:

[0008] 1. Use permanent magnets to generate magnetic force for non-contact stirring, which saves energy and costs, keeps the metal slurry free from pollution, and has no dead angles in stirring.

[0009] 2. High quality. Due to the effect of rotating centrifugal force, the permanent magnetic stirring method usually used often forms a vortex in the center of the slurry, making it easy for gas to be drawn into the metal slurry, and the solid particles formed are easy to gather on the inner wall of the container, thereby affecting the quality of the semi-solid slurry. The present invention sets a cooling mechanism in the center of the container, which can not only increase the cooling speed of the slurry, but also avoid the formation of a vortex in the middle of the metal slurry, and can make the solid particles run inside and outside the container, thereby preparing high-quality metal semi-solid slurry.

[0010] 3. High efficiency. The cooling mechanism adopts liquid circulation cooling, which has a fast cooling speed. Combined with the unique structural design of the cooling head and the efficient permanent magnetic stirring method, the semi-solid preparation efficiency is greatly improved. The fastest time to prepare 3 kg of semi-solid aluminum alloy slurry with a solid phase ratio of 25% is 8 seconds.

[0011] 4. Wide slurry making range. It can prepare semi-solid metal slurry with a solid phase ratio of 5%-60%, and the weight range of the prepared slurry is 0.1-60 kg.

[0012] 5. Low cost. The pulping cost per kilogram is no more than 0.1 yuan, which is conducive to large-scale production and application and promotes the development of the foundry industry.

[0013] In recent years, the application of semi-solid preparation technology has become more and more extensive in the world, especially in my country, which has been the world's number one in terms of application scale. At present, there are dozens of semi-solid preparation methods on the market, but most of them are not only inefficient, but also easily involve gases and form oxide scales during the pulping process, which affect the semi-solid slurry. The present invention solves the common problems existing in the above-mentioned existing semi-solid preparation technology and can quickly produce high-quality metal semi-solid slurry. It can well promote the further development of my country's foundry industry, obtain higher quality castings, and improve the technical level of industries such as automotive lightweighting, aerospace, high-speed rail, and communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of an embodiment of a device for rapidly preparing semi-solid metal slurry according to the present invention.

[0015] Figure 2 yes Figure 1 Top view of the .

[0016] Figure 3 The invention discloses a metallographic structure diagram of a casting after the semi-solid aluminum alloy slurry is prepared by the present invention and then subjected to die casting.

[0017] Explanation of reference numerals: 1 container, 11 reflective protrusion, 2 permanent magnetic stirring mechanism, 21 rotating barrel, 22 permanent magnetic magnet group, 23 motor, 24 transmission gear group, 3 cooling mechanism, 31 coolant delivery core, 311 annular cooling groove, 312 liquid inlet channel, 313 liquid outlet channel, 32 sealing sleeve, 33 cooling head, 331 arc-shaped spoiler groove, 4 gas protection mechanism, 41 blowing nozzle, 5 metal slurry. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and embodiments:

[0019] like Figure 1 and 2 Shown is a schematic diagram of an embodiment of a device for rapidly preparing semi-solid metal slurry provided by the present invention.

[0020] A device for rapidly preparing semi-solid metal slurry, comprising a container 1 for placing the metal slurry, a permanent magnetic stirring mechanism 2 for driving electromagnetic stirring of the metal slurry in the container 1, and a cooling mechanism 3 for cooling the metal slurry;

[0021] The cooling mechanism 3 comprises a cooling liquid delivery core 31 and a conductive seal. The cooling liquid delivery core 31 is arranged vertically, and the outer peripheral wall of the lower section thereof is provided with an annular cooling groove 311. Preferably, the cooling liquid delivery core 31 should be located at the central axis of the container 1.

[0022] The conductive seal is sleeved on the lower section of the coolant delivery core 31, and its inner wall and the annular cooling groove 311 form a cooling channel. The coolant delivery core 31 is also provided with a liquid inlet channel 312 and a liquid outlet channel 313 connected to the cooling channel.

[0023] The conductive seal is located inside the cavity of the container 1, and a plurality of vertically extending arc-shaped spoiler grooves 331 are formed on the outer peripheral wall of the conductive seal. The arc-shaped spoiler grooves 331 are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center.

[0024] The inner peripheral wall of the container 1 is provided with a plurality of vertically extending reflective protrusions 11, and the reflective protrusions 11 are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center.

[0025] During the stirring process, the metal slurry will gather toward the outside due to the centrifugal force, and when it encounters the reflective protrusion 11 , the metal slurry can be reflected and flow toward the cooling mechanism 3 in the middle.

[0026] The reflective protrusion 11 is correspondingly arranged on the outer side of the middle area of ​​the two arc-shaped spoiler grooves 331 .

[0027] The conductive seal comprises a sealing sleeve 32 sleeved on the outside of the annular cooling groove 311 and a cooling head 33 connected to the outside of the sealing sleeve 32 ; the arc-shaped spoiler groove 331 is arranged on the outer peripheral wall of the cooling head 33 .

[0028] The arc-shaped spoiler groove 331 is a concave arc-shaped groove body, and the reflective protrusion 11 is an arc-shaped protrusion.

[0029] The number of the arc-shaped spoiler grooves 331 and the reflective protrusions 11 is the same, and they are staggered at a certain angle.

[0030] The sealing sleeve 32 can quickly absorb the heat on the cooling head 33 and quickly take away the heat through the coolant circulating in the cooling channel.

[0031] The sealing sleeve 32 and the cooling head 33 are connected and fixed via a threaded structure.

[0032] The upper and lower ends of the sealing sleeve 32 can be sealed and fixed on the coolant delivery core 31 by welding.

[0033] The cooling head 33 is made of a composite material composed of cubic boron nitride and aluminum nitride, and has a thermal conductivity of more than 110 W / m·K. It is non-sticky and non-magnetic.

[0034] The coolant delivery core 31 is made of non-magnetic stainless steel.

[0035] The sealing sleeve 32 is made of copper and is non-magnetic.

[0036] The container 1 is made of high temperature and corrosion resistant silicon carbide ceramic material, which is non-magnetic, non-sticky, has good heat preservation effect and long service life.

[0037] The present invention also includes a gas protection mechanism 4, which includes an inert gas supply source and a plurality of blowing nozzles 41 connected to the inert gas supply source; the blowing nozzles 41 are arranged above the container 1, and the gas outlets thereof face the metal slurry surface at the lower side.

[0038] The blowing nozzles 41 are connected to the annular stainless steel air pipe, and the number can be 6-10.

[0039] The blowing nozzles 41 are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center.

[0040] The blowing nozzle 41 continuously blows inert gas toward the surface of the metal slurry in the container 1 to protect the metal slurry from inhaling oxygen during the stirring process and to avoid the generation of oxide scale, so as to ensure that a pure semi-solid metal slurry is obtained.

[0041] The permanent magnetic stirring mechanism 2 includes a rotating barrel 21 , a permanent magnetic magnet group 22 arranged on the inner wall of the rotating barrel 21 , a motor 23 driving the rotating barrel 21 to rotate, and a transmission gear group 24 connecting the motor 23 and the rotating barrel 21 .

[0042] The implementation steps of the present invention are as follows:

[0043] 1. Put metal slurry with a temperature 10-40°C higher than its liquidus temperature into container 1. The metal slurry is a molten alloy, which can be an aluminum alloy, a magnesium alloy, a zinc alloy or a copper alloy.

[0044] 2. Inject coolant into the coolant delivery core to cool the cooling head 33.

[0045] 3. The cooling mechanism 3 descends, enters the center of the container, and stops at a set depth. The depth setting distance is 10-40 mm from the bottom of the cooling head 33 to the bottom of the container 1.

[0046] 4. The gas protection mechanism 4 is started to blow inert gas into the container 1 to isolate the surface of the metal slurry in the container 1 from the air, thereby preventing the metal slurry from being drawn into the air during the stirring process.

[0047] 5. The permanent magnetic stirring mechanism 2 is started, and the motor 23 drives the rotating barrel 21 to rotate at a high speed, and the rotation speed is set to 200 to 600 revolutions per minute. The rotation time can be set to 5-50 seconds according to different solid phase ratio requirements.

[0048] The permanent magnet group 22 rotates rapidly under the drive of the rotating barrel 21 , and generates a strong rotating magnetic field during the rotation process, thereby driving the metal slurry in the container 1 to rotate, playing the role of stirring the metal slurry.

[0049] The dendritic structure of the liquid metal is broken into nearly spherical crystals under the intense stirring action. The metal slurry will continuously contact the cooling head 33 placed in the middle of the container 1 during the rotational motion, which accelerates the cooling rate of the metal slurry and makes it difficult for the spherical grains of the semi-solid component to become larger, thereby achieving the purpose of quickly preparing the slurry.

[0050] Generally, the metal slurry will be thrown outward due to the centrifugal force during high-speed rotation, and the metal slurry (especially the solid particles in the metal slurry) will gather on the inner peripheral wall of the container 1. To avoid this situation, the present invention provides a plurality of vertically extending reflective protrusions 11 on the inner peripheral wall of the container 1, and provides an arc-shaped spoiler groove 331 on the outer peripheral wall of the cooling head 33.

[0051] When the high-speed rotating metal slurry hits the reflective protrusion 11, it will flow toward the middle cooling head 33. When the metal slurry hits the arc-shaped spoiler groove 331 of the cooling head 33, it will be reflected outward again, and then hit the reflective protrusion 11 on the inner wall of the container 1, and then reflect to the next arc-shaped spoiler groove 331 of the cooling head 33, so that the metal slurry can be evenly and fully cooled and stirred, and finally high-quality semi-solid metal slurry is prepared.

[0052] 6. After the stirring is completed, the permanent magnetic stirring mechanism 2 stops, the cooling mechanism 3 rises back to the origin, and the container 1 rises and moves out of the rotating barrel 21, thus preparing the metal semi-solid slurry.

[0053] Figure 3 This is a metallographic photograph of a casting formed by die-casting of semi-solid slurry of aluminum alloy, showing that its spheroidal crystal structure is evenly distributed with an average diameter of no more than 50um. Its mechanical properties and thermal conductivity are better than those of castings formed by die-casting of ordinary liquid aluminum alloy.

Claims

1. A device for rapidly preparing semi-solid metal slurry, characterized in that: It comprises a container (1) for placing metal slurry, a permanent magnetic stirring mechanism (2) for driving electromagnetic stirring of the metal slurry in the container (1), and a cooling mechanism (3) for cooling the metal slurry; The cooling mechanism (3) comprises a cooling liquid conveying core (31) and a conductive seal. The cooling liquid conveying core (31) is arranged vertically, and an annular cooling groove (311) is provided on the outer peripheral wall of the lower section. The conductive seal is sleeved on the lower section of the coolant delivery core (31), and its inner wall and the annular cooling groove (311) form a cooling channel. The coolant delivery core (31) is also provided with a liquid inlet channel (312) and a liquid outlet channel (313) which are connected to the cooling channel. The conductive seal is located inside the cavity of the container (1), and a plurality of vertically extending arc-shaped spoiler grooves (331) are formed on the outer peripheral wall of the conductive seal, wherein the arc-shaped spoiler grooves (331) are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center; The inner peripheral wall of the container (1) is provided with a plurality of vertically extending reflective protrusions (11), and the reflective protrusions (11) are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center; The reflective protrusion (11) is correspondingly arranged on the outside of the middle area of ​​the two arc-shaped spoiler grooves (331); The conductive seal comprises a sealing sleeve (32) sleeved on the outside of the annular cooling groove (311) and a cooling head (33) connected to the outside of the sealing sleeve (32); the arc-shaped spoiler groove (331) is arranged on the outer peripheral wall of the cooling head (33).

2. The device for rapidly preparing semi-solid metal slurry according to claim 1, characterized in that: The sealing sleeve (32) and the cooling head (33) are connected and fixed via a threaded structure.

3. The device for rapidly preparing semi-solid metal slurry according to claim 1, characterized in that: The material of the cooling head (33) is a composite material composed of cubic boron nitride and aluminum nitride; the material of the coolant delivery core (31) is a non-magnetic stainless steel material; and the material of the sealing sleeve (32) is red copper.

4. The device for rapidly preparing semi-solid metal slurry according to claim 1, characterized in that: It also includes a gas protection mechanism (4), which includes an inert gas supply source and a plurality of blowing nozzles (41) connected to the inert gas supply source; the blowing nozzles (41) are arranged above the container (1), and their gas outlets face the metal slurry surface at the lower side.

5. The device for rapidly preparing semi-solid metal slurry according to claim 4, characterized in that: The air blowing nozzles (41) are symmetrically distributed in a ring shape with the central axis of the conductive seal as the center.

6. The device for rapidly preparing semi-solid metal slurry according to any one of claims 1 to 5, characterized in that: The permanent magnetic stirring mechanism (2) comprises a rotating barrel (21), a permanent magnetic magnet group (22) arranged on the inner wall of the rotating barrel (21), a motor (23) for driving the rotating barrel (21) to rotate, and a transmission gear group (24) connecting the motor (23) and the rotating barrel (21).

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