CN112452258A

CN112452258A - High-efficient preparation facilities of light alloy semi-solid slurry composite stirring

Info

Publication number: CN112452258A
Application number: CN202011248199.1A
Authority: CN
Inventors: 王开坤; 王林春; 胡志强; 杨森
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2021-03-09

Abstract

The invention discloses a light alloy semi-solid slurry composite stirring high-efficiency preparation device which comprises a driving motor, a temperature control device, a connecting guide pipe, a stirrer lifting mechanism and a crucible for placing alloy melt. Before the stirrer extends into the alloy melt, the temperature control device starts to introduce high-temperature gas into the stirrer, so that the stirrer is positioned in an alloy semi-solid temperature region or a region close to the alloy semi-solid temperature region, and surface chilling is avoided when the stirrer extends into the alloy melt. The cooling channel is added in the blade, so that the alloy melt can be quickly cooled to a semi-solid temperature range. Meanwhile, the cooling channel in the blade is provided with a through hole, cooling gas enters the alloy melt through the through hole, and the preparation efficiency of the semi-solid slurry is accelerated under the synergistic action of gas stirring and mechanical stirring. The synergistic action of shearing and cooling can destroy the growth environment of dendritic crystal, so that the alloy melt can generate near-spherical particles in the environment with uniform temperature, and good semi-solid slurry can be obtained.

Description

High-efficient preparation facilities of light alloy semi-solid slurry composite stirring

Technical Field

The invention relates to the field of semi-solid metal processing, in particular to a preparation device for light alloy semi-solid slurry composite stirring.

Background

The semi-solid metal processing has attracted attention since the invention of the 20 th century and the 70 th century because of the good forming performance, and is praised as one of the leading processing technologies of the 21 st century by most scientists along with the improvement of the process technology. The semi-solid metal slurry is used as the most important ring in the semi-solid metal processing technology, and the quality of the semi-solid metal slurry determines the quality of a formed product. There are generally two ways to obtain a nearly spherical semisolid tissue: (1) enough nucleation cores are obtained, the growth process of crystal grains is controlled, the growth of dendrites is inhibited, and the growth of the crystal grains is inhibited; (2) and (3) carrying out strong shearing on the solid-phase particles to break the dendritic crystals. Based on the mechanism used in the process of preparing the semi-solid metal slurry, the preparation process of the semi-solid slurry can be divided into three types: nucleation growth control, stirring/shearing, nucleation + stirring/shearing. Common stirring methods for semi-solid metal slurry include mechanical stirring, electromagnetic stirring, bubble stirring, low superheat casting, ultrasonic wave treatment, and spray deposition. The mechanical stirring method is accepted by most semisolid processing enterprises due to the low cost, simple device, high production efficiency and good slurry quality, so that how to reduce the semisolid processing cost by using simple equipment and realize better semisolid slurry is the aim of continuous exploration of scientific researchers.

Chinese patent No. 202010522127.5 proposes a semi-solid slurry integrated system of a spiral pipe, which proposes that the alloy melt moves in the spiral pipe by using the self gravity of the alloy melt, and the alloy melt is turned and sheared in the flowing process by using the special structure of the spiral pipe. The rotation angle of the spiral pipe can be realized by the up-and-down movement of the top plate, so that the shearing force is changed. The high-intensity rolling and shearing action is matched with the design of the cooling pipe, so that the fine dendritic crystals just formed in the metal melt are immediately broken to form fine and round particles. However, the method is easy to cause the sticking of the material on the surface of the spiral pipe, and the special structure of the spiral pipe causes the difficulty in cleaning, needs continuous cleaning, has low production efficiency and high cost, and is not beneficial to industrialized large-scale production.

The Chinese patent with the application number of 202010593736.X discloses a conical barrel type semi-solid metal slurry preparation device, which designs two layers of protective shells, wherein a storage outer cavity is arranged inside a first protective shell, and a first discharge hole is arranged at the lower end of the first protective shell; and a feeding mechanism is arranged at the upper end of the material storage mechanism and comprises an annular conveying pipe and a second protective shell. According to the invention, the accumulation of raw materials is avoided through the special feeding mechanism, and the efficiency of the device can be improved through the larger shearing force formed by the reverse mechanism. However, the device has complex design and higher cost, increases the cost of semi-solid metal processing, is not beneficial to industrialized popularization, and the annular conveying pipe also has the problem of difficult cleaning, thereby increasing the difficulty of large-scale industrialization.

The document "Microstructure EVOLUTION OF Al-Si SEMI-SOLID SLURRY BY GAS STIRRING METHOD (Zhang Lei, Dongpu, Li Ji et Al. MICRO TRUCTURE EVOLUTION OF AL-SI SEMI-SOLID SLURRY BY GAS BUBBLE STRING METHOD [ J ]. school OF south China university (English edition), 2011, (6):1789, 1794.") proposes a METHOD for preparing Al-Si alloy SEMI-SOLID SLURRY BY GAS STIRRING. The paper used a helical tubular graphite stirrer with a small hole of 1mm diameter in its wall. The graphite stirrer is connected with the argon steel cylinder through a hollow stirring rod. The stirrer and stirring rod are rotated by a motor through a transmission belt. Thus, argon gas may be introduced into the melt by a rotating graphite stirrer. Under the action of buoyancy of the melt and centrifugal force generated by the rotary graphite stirrer, bubbles rise in the melt and form a spiral motion curve, so that strong convection and weak stirring effects are generated on the melt. However, the method only uses single gas stirring, the preparation efficiency of the semi-solid slurry is low, and the preparation of the slurry is limited by the volume of equipment, so that the requirement of large-scale production cannot be met.

Disclosure of Invention

The invention aims to provide a semi-solid metal slurry preparation device which is simple in structure, low in production cost and high in working efficiency, and solves the problem that the semi-solid processing cost of light alloy is high and large-scale industrialization is difficult.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a light alloy semi-solid slurry composite stirring preparation facilities, the device includes driving motor, temperature control device, connecting conduit, agitator elevating system and is used for placing the crucible of alloy fuse-element. The stirrer extends into the melt and is provided with a stirring end and a ventilation end, and the end connected with the connecting conduit is connected with the temperature control device through the connecting conduit. Before the stirrer extends into the alloy melt, the temperature control device starts to introduce high-temperature gas into the stirrer, so that the stirrer is positioned in an alloy slurry semi-solid temperature range or a temperature range close to the alloy slurry semi-solid temperature range, and the surface chilling generated when the stirrer extends into the alloy melt is avoided. The cooling channel is added into the blade, so that the alloy melt can be rapidly cooled to a semi-solid temperature range. Meanwhile, the cooling channel in the blade is provided with the air hole, and when cooling gas enters the alloy melt through the opening, the preparation efficiency of the semi-solid slurry is accelerated under the synergistic action of gas stirring and mechanical stirring. The synergistic effect of shearing and cooling can destroy the growth environment of dendritic crystal, so that the alloy melt can generate near-spherical particles in an environment with relatively uniform temperature, and good semi-solid slurry can be obtained. The inclined blades can prevent the stirrer from generating vortex during stirring and destroy the liquid level structure to oxidize the alloy slurry; the six blades rotate forward and backward at a small angle of 60 degrees and can well avoid the generation of vortexes during stirring, so that the damage to the liquid level is reduced, and the quality of the alloy melt is better maintained.

In the present invention, the stirring device includes a stirrer section, a driving motor, and a temperature control device. The stirrer part comprises puddler and blade, the puddler passes through the gear train structure in the stirring part and is connected with driving motor, through connecting pipe with temperature control device connects.

The stirring rod of the stirring part is of a hollow structure, a central pipeline extends to the stirring end of the stirrer, the diameter of the central pipeline is 5-50 mm, and the outer diameter range is 8-100 mm;

the stirrer is characterized in that blades are arranged at the stirring end of the stirrer part, the number of the blades is 1-10, the number of each group of blades is 3-12, the included angle between each blade and the axis of a stirring rod of the stirrer is 10-45 degrees, the cross section of a cooling channel in each blade of the stirrer is circular in shape, and the diameter range of the cooling channel of each blade of the stirrer is preset to be 0.5-10 mm. The preset diameter range of the through hole on the stirrer blade is 50 um-5 mm;

wherein the rotation angle of the stirrer ranges from 60 degrees to 360 degrees.

In the invention, the stirrer can be designed into a cone shape or a barrel shape according to the structure of an actual crucible or a bearing container so as to realize the sufficient stirring of the slurry.

In the invention, a fixing bracket is welded at the upper end of the stirrer and positioned outside the driving motor, and a temperature control device is also welded on the fixing bracket.

In the present invention, the driving motor and the agitator are combined by a set of meshed gear sets, and the rotation speed of the agitator can be realized by adjusting the rotation speed of the driving motor or the module ratio of the gear sets.

In the invention, the gas used by the temperature control device is inert gas such as argon or other gas which does not react with the alloy melt.

In the present invention, the temperature control device is linked with the central pipe of the stirrer through a connecting conduit, and the material of the connecting conduit includes, but is not limited to, rubber composite material, plastic composite material and metal material.

In the invention, the light alloy semi-solid slurry preparation device used for any one of the above steps comprises the following steps:

s1: fixing the stirring device at the lower end of a lifting mechanism which is arranged in a matched manner, and then starting the lifting mechanism to adjust the position of the stirring device;

s2: starting a ventilation temperature control device, adjusting the temperature of gas to be in a high-temperature state, introducing high-temperature gas into the stirrer blade through the connecting pipeline and the central pipeline, and ventilating for a period of time to enable the stirrer blade to reach a preset temperature;

s3: starting a lifting mechanism, extending the stirrer into the alloy slurry, and starting a driving motor to enable the stirrer to start to work;

s4: detecting the temperature of the alloy melt through a temperature sensor, driving a motor to stop working after the temperature reaches the expected temperature, stopping the work of a ventilation temperature control device, and moving a stirrer out of the melt through a lifting mechanism;

s5: and cleaning and maintaining the device after the semi-solid slurry is prepared.

Compared with the prior art, the invention has the following beneficial effects:

(1): according to the invention, through the special blade structure and the design of a blade cooling channel cooling method, the cooling of the alloy melt can be accelerated, and the preparation efficiency of the semi-solid slurry is accelerated;

(2): according to the invention, the blades are provided with the air holes in the area of the cooling channel, and air enters the alloy melt from the air holes to play a role in air stirring and form a synergistic effect with the mechanical stirring of the stirrer, so that the stirring efficiency is increased;

(3): the minimum rotation angle of the blade can be 60 degrees, and the generation of vortex can be avoided by a smaller rotation angle, so that the damage to a liquid surface structure is avoided, and the oxidation of alloy slurry is reduced;

(4): according to the invention, the included angle between the stirrer blade and the stirring rod is 10-45 degrees, and the inclined angle can reduce the generation of vortex of the alloy melt during stirring, reduce the damage to the liquid level and reduce the oxidation of the alloy slurry; meanwhile, the inclined angle can realize higher stirring speed;

(5): the temperature control device continuously outputs high-temperature gas, so that the stirrer is positioned in a semi-solid temperature range of the alloy melt or in a semi-solid temperature range close to the alloy melt in the stirring process, the alloy melt is positioned in a more uniform temperature field, and the size of the formed semi-solid particles is more uniform and finer.

Drawings

FIG. 1 is a schematic structural diagram of a semi-solid metal slurry preparation apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic view of a stirring rod according to a first embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a blade of a stirrer according to a first embodiment of the present invention;

FIG. 4 is a schematic structural view of a semi-solid metal slurry preparing apparatus according to a second embodiment of the present invention;

fig. 5 is a schematic structural view of a stirring rod according to a second embodiment of the present invention.

Fig. 6 is a schematic structural view of a stirring rod according to a second embodiment of the present invention.

Detailed Description

The following further describes the embodiments of the present invention with reference to the drawings.

The first embodiment is as follows:

referring to fig. 1, a light alloy semi-solid slurry preparation apparatus shown in this embodiment includes a ventilation temperature control device 1, a connection conduit 2, a stirrer 3, a gear set 4, a driving motor 5, stirrer blades 6, and a carrying device 9. In the embodiment, argon is introduced as cooling gas to realize the control of the temperature of the alloy melt.

Referring to fig. 2, it is shown that the stirring rod is a hollow structure, the central pipe of the stirring rod extends to the stirring end along the axial direction, the central pipe is a stirrer gas inlet channel, the stirring rod is provided with an opening connected with the gas inlet of the blade, and the gas enters the alloy melt from the through hole through the cooling channel.

Referring to fig. 1-4, in the apparatus for preparing semi-solid metal slurry, one end of the stirrer 3 extending into the alloy slurry 7 is a stirring end, referring to fig. 2, a structural schematic diagram of the stirrer is shown, referring to fig. 3, a structural schematic diagram of a stirring rod of the stirrer is shown, and the ventilation temperature control device 1 delivers gas to the stirrer 3 through the connecting conduit 2. In the stirrer 3, gas enters the stirring rod from the gas inlet channel 31, then enters the

gas inlet channels

41 and 42 of the stirrer blade 4 through the channels 32 and 33, passes through the cooling channel of the stirrer blade, and enters the alloy melt from the blade through hole 43.

Referring to the blade structure of the stirrer in fig. 4, gas flows into the blades from the

gas inlets

41 and 42, flows out of the gas holes 43 after passing through the cooling channel, and the cooling channel keeps a higher temperature when the blades extend into the alloy melt, so that the blades are chilled when extending into the alloy melt due to a larger temperature difference, and can guarantee a lower temperature while stirring, so that a more uniform temperature field can be maintained while cooling the alloy is accelerated, the growth environment of dendrites is damaged, and thus semi-solid slurry with uniformly distributed solid particles is obtained. And air holes with the diameter of 50-5 mm are arranged at other positions provided with the channels, and cooling gas enters the alloy melt from the through holes to form gas stirring, so that the stirring efficiency is enhanced.

The stirring rod in the embodiment is preferably cylindrical, and can be adjusted to be a stirring rod with other shapes according to actual requirements; in this embodiment, the stirrer blade is preferably rectangular, and may be adjusted to other shapes according to actual conditions. The material of the stirring rod and the blades in the embodiment can adopt stainless steel, graphite, die steel, cast iron and high-temperature copper alloy.

In the present embodiment, in order to improve the stirring efficiency and effect, the number of blades and the distance between each group of blades can be adjusted.

In the present embodiment, the temperature of the stirrer blades may be passed through other gas or inert gas which does not react with the alloy melt.

Example II

On the basis of the first embodiment, the use method of the semi-solid metal slurry preparation device is disclosed by taking A356 aluminum alloy as an example, and comprises the following steps:

s1, heating the A356 to 700 ℃, standing for 2-3 min after the alloy is completely melted, and then transferring the alloy melt into a crucible 9 for stirring;

s2: fixing the stirring device at the lower end of a lifting mechanism which is arranged in a matched manner, and then starting the lifting mechanism to adjust the position of the stirring device;

s3: starting the ventilation temperature control device 1, outputting high-temperature argon according to the preset gas temperature of 550 ℃, introducing the high-temperature argon into the stirrer blades from the

gas inlets

41 and 42 through the connecting pipeline 2 and the central pipeline 31, and ventilating for 10-30 min to enable the stirrer to reach the preset temperature of 550 ℃;

s4: starting a lifting mechanism, extending the stirrer 3 into the alloy slurry 7, and starting a driving motor 5 to enable the stirrer 3 to start working;

s5: detecting the temperature of the alloy melt through a temperature sensor, driving the motor 5 to stop working after the temperature reaches the expected temperature, stopping the ventilation temperature control device 1, and moving the stirrer 3 out of the melt through the lifting mechanism;

s6: and cleaning and maintaining the device after the semi-solid slurry is prepared.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the scope of the present invention.

Claims

1. The utility model provides a high-efficient preparation facilities of light alloy semi-solid slurry composite stirring which characterized in that includes: the device comprises a driving motor, a temperature control device, a connecting guide pipe, a stirrer lifting mechanism and a crucible for placing alloy melt. The stirrer extends into the melt and is provided with a stirring end and a ventilation end, and the end connected with the connecting conduit is connected with the temperature control device through the connecting conduit.

2. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in claim 1, wherein the stirring blade is provided with a cooling channel therein, and an air inlet of the blade cooling channel is connected with the central pipeline. And cooling gas is introduced into the cooling channel during stirring to cool the blades so as to reduce the temperature of the alloy melt, and the preparation of the semi-solid slurry can be accelerated under the synergistic effect of cooling and shearing.

3. A composite stirring high-efficiency preparation device of light alloy semi-solid slurry as claimed in claim 2, wherein the stirring blade is provided with air holes on the cooling channel, and the cooling gas is introduced into the alloy melt through the air holes on the cooling channel when the cooling gas flows in the cooling channel, so that the synergistic effect of gas stirring and mechanical stirring by the rotation of the blade is formed, the shearing effect is increased, and the preparation efficiency of the semi-solid slurry is accelerated.

4. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in claim 3, wherein the stirrer blade and the stirrer stirring rod form a certain included angle, and the inclined angle can prevent an alloy melt from generating vortex during stirring, reduce damage to a liquid level and reduce oxidation of the alloy slurry; and meanwhile, the inclined angle can realize higher stirring speed.

5. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in claim 4, wherein the rotation angle of the stirrer during stirring in the alloy melt is 60-360 degrees, the rotation direction of the stirrer is controlled by the driving motor, and forward rotation and reverse rotation can be realized. Wherein, the alloy melt hardly generates vortex when rotating forward and backward at 60 degrees, and the damage to the liquid level is extremely small.

6. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as recited in claim 5, wherein the temperature control device continuously generates high-temperature gas to enable the stirrer to be in an alloy semi-solid temperature region or a region close to the alloy semi-solid temperature region, so that the alloy melt is in a uniform temperature field during stirring, and the formed semi-solid particles are more uniform and finer.

7. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as recited in claim 6, wherein the stirrer is preheated before stirring, that is, the temperature control device feeds high-temperature gas into the stirrer before stirring is started, and after the stirrer reaches a predetermined temperature, the stirring end of the stirrer is extended into the alloy melt, and the stirrer starts to work.

8. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in any one of claims 1 to 7, further comprising a driving motor connected with the stirrer stirring rod through a gear set, wherein different rotation speed ratios of the driving motor and the stirrer can be realized by replacing gear sets with different modulus ratios; and controlling the rotating speed of the stirrer by a speed sensor integrated in the driving motor, wherein the preset rotating speed of the driving motor is 0-1200 r/min.

9. A composite stirring high-efficiency preparation device for light alloy semi-solid slurry as claimed in any one of claims 1 to 7, wherein the gas flow rate of the temperature control device is controlled by a sensor integrated in the temperature control device, and is preset to be 0-800L/min.

10. A composite stirring high-efficiency preparation device for light alloy semi-solid slurry as claimed in any one of claims 1 to 7, wherein the included angle between the stirrer blade and the axis of the stirrer rod of the stirrer is 10-45 °.

11. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in any one of claims 1 to 7, wherein the cross-sectional shape of the cooling channel in the stirrer blade is circular or the like, and the diameter range of the cooling channel of the stirrer blade is preset to be 0.5mm to 10 mm.

12. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in any one of claims 1 to 7, wherein the preset diameter range of the air holes of the stirrer blades is 50um to 5 mm.

13. A composite stirring high-efficiency preparation device of a light alloy semi-solid slurry as claimed in any one of claims 1 to 7, wherein the gas generated by the temperature control device is inert gas such as high-temperature argon and other gases which do not react with the metal melt.

14. A method for preparing a semi-solid metal slurry by using the light alloy semi-solid slurry composite stirring high-efficiency preparation device as claimed in any one of claims 1 to 13, which comprises:

heating the alloy to a molten state in the crucible, or pouring the molten alloy directly into the crucible;

opening the temperature control device to introduce high-temperature gas into the stirrer blade at a preset gas flow rate until the temperature of the stirrer reaches a preset temperature;

stretching the stirring end of the stirrer into the alloy melt liquid surface, simultaneously turning on the driving motor, and stirring according to the preset rotating speed, rotating direction and angle;

through temperature sensor detects the alloy fuse-element and cools down to the uniform temperature, stops the agitator with temperature control device's work carries equipment such as die casting machine with the semi-solid slurry of preparation and realizes semi-solid metal processing.