阅读说明：本技术 一种微固态成型工艺及装置 (Micro-solid forming process and device ) 是由 杨林龙 郭会廷 于 2021-06-08 设计创作，主要内容包括：本发明是一种微固态成型工艺及装置,包括步骤1)利用压力将金属液从保温炉中通过中间管路向模型型腔流动；步骤2)在中间管路上控制其管壁温度,由于管壁温度低于金属也液相线使得部分金属液沿着管壁产生固相,长出凝固枝晶；步骤3)将长出的凝固枝晶打碎细化并弥散分布在金属液中成为形核核心,破碎细化并且弥散分布后的形核核心使得金属液呈现仍然具有较高流动性的微固态；步骤4)将呈微固态的金属液流入模型型腔浇注成型。本发明兼具了液态与半固态的优点,既可以形成复杂结构铸件,又可以在一定程度上提升铸件的质量、提高工艺出品率、节约原材料的消耗,温度调节灵活,应用范围广泛。(The invention relates to a micro-solid forming process and a device, which comprises the following steps of 1) utilizing pressure to make molten metal flow from a heat preservation furnace to a model cavity through an intermediate pipeline; step 2) controlling the temperature of the pipe wall of the middle pipeline, and enabling part of molten metal to generate a solid phase along the pipe wall and grow solidified dendritic crystals as the temperature of the pipe wall is lower than the liquidus of the metal; step 3) breaking, thinning and dispersing the grown solidified dendrites in the metal liquid to form nucleation cores, wherein the nucleation cores after breaking, thinning and dispersing distribution enable the metal liquid to be in a micro-solid state with high fluidity; and 4) pouring the micro-solid metal liquid into a mold cavity for molding. The invention has the advantages of both liquid state and semi-solid state, can form castings with complex structures, can improve the quality of the castings to a certain extent, improve the process yield, save the consumption of raw materials, and has flexible temperature regulation and wide application range.)

1. A micro-solid state molding process is characterized by comprising the following steps:

step 1) utilizing pressure to enable molten metal to flow from a heat preservation furnace to a model cavity through an intermediate pipeline;

step 2) controlling the pipe wall temperature of the intermediate pipeline so as to:

the temperature of the molten metal close to the central part of the middle pipeline is higher than the liquidus temperature of the molten metal, so that the molten metal is maintained in a liquid phase;

the temperature of the metal liquid close to the pipe wall part of the middle pipeline is lower than the liquidus temperature of the metal liquid, so that the metal liquid generates a solid phase and solidified dendritic crystals grow;

step 3) arranging a stirring device around the intermediate pipeline, stirring the molten metal in the molten metal when the molten metal flows through the intermediate pipeline, so that the grown solidified dendritic crystals are broken, refined and dispersed in the molten metal to form nucleation cores when the molten metal is solidified, and the nucleation cores after refining and dispersion distribution enable the molten metal to be in a micro-solid state with high fluidity;

and 4) continuously applying pressure to the micro-solid metal liquid to enable the metal liquid to flow into a mold cavity, stopping a gate of the mold cavity after the mold cavity is filled, finishing the pouring process, and removing the poured casting to prepare for pouring of the next mold.

2. The micro solid state molding process of claim 1, wherein the intermediate pipeline is a lift pipe, and the molten metal in the holding furnace flows from bottom to top to the mold cavity through the lift pipe under the action of pressure.

3. The micro solid state forming process of claim 1, wherein the temperature of the pipe wall of the intermediate pipe and the temperature of the molten metal in the holding furnace are controlled, after stirring, the temperature of the molten metal is divided and controlled to seven levels of L0-L7 before entering the mold cavity, and the temperature Δ t is an interval temperature below the molten metal phase line₀At a minimum temperature level L0, with each additional interval temperature Δ t₀In one grade, up to the L7 grade, each grade temperature corresponds to a different solid fraction and fluidity.

4. The micro solid state forming process of claim 1, wherein the stirring device is an electromagnetic stirring device, and the molten metal is stirred in a rotating manner without contacting with the molten metal.

5. A micro-solid forming device is characterized by comprising a heat preservation furnace, a liquid lifting pipe and a model cavity, wherein one end of the liquid lifting pipe is communicated with the heat preservation furnace, and the other end of the liquid lifting pipe is communicated to the bottom of the model cavity.

6. The apparatus according to claim 5, wherein the holding furnace is provided with a furnace cover and a corresponding pressurizing port at the top thereof, so that a sealed cavity is formed inside the holding furnace to facilitate the application of pressure, and the lift pipe passes through the furnace cover from the top into the holding furnace.

7. A micro-solid forming device according to claim 6, wherein the riser tube is provided at its periphery with an electromagnetic stirring device for non-contact stirring of the molten metal flowing through the riser tube.

8. The apparatus of claim 7, wherein the electromagnetic stirring device is disposed at the periphery of the lift tube at the exposed portion between the holding furnace and the mold cavity.

Technical Field

The invention relates to the technical field of metal casting, in particular to a micro-solid forming process and a micro-solid forming device.

Background

At present, casting is classified into liquid casting and semi-solid casting according to the state of liquid metal.

The liquid metal is completely liquid at a temperature above the liquid phase, has good fluidity, is easy to form a complex structure, is a traditional casting mode, and has the defects that the gas content of the liquid metal is relatively high, and air holes and air shrinkage holes are easily formed on a casting; in the solidification process, the liquid state is converted into the solid state, the material shrinks, shrinkage porosity and shrinkage cavity are easy to form, or extra material is needed for feeding, so that the process yield of the product is low; the solidification speed is slow, crystal grains are easy to grow up, the structure is large, and the mechanical property is reduced.

Semi-solid casting, namely metal semi-solid forming, means that materials can be carried like solid metal in the process of metal phase transformation from solid to liquid or from liquid to solid; the material has certain rheological property, and certain pressure is applied to form a required structure; the method has the advantages of high solidification and cooling speed, fine crystal grains, less tissue defects, small shrinkage rate, easy realization of near-net shape forming and relatively high mechanical property of a product; the method has the disadvantages that the fluidity is poor, a complex casting with an inner cavity structure is difficult to form, and the required pressure is high during molding, generally dozens of megapascals are required, so the equipment cost investment is high.

In summary, the current liquid casting and semi-solid casting have advantages, but have disadvantages, which are difficult to solve.

Aiming at the problems, the invention provides a micro-solid forming process and a micro-solid forming device, so that metal is in a molten metal state between a liquid state and a semi-solid state, the molten metal is subjected to process treatment, a nucleation core in the molten metal is increased, the good fluidity is ensured, the gas content in the molten metal is reduced, grains are refined, the structure is improved, the heat conduction to a cavity is reduced, the thermal deformation of a sand mold and a sand core is reduced, the size precision of a casting is improved, and the feeding amount is reduced.

Disclosure of Invention

The invention aims to overcome the problems in the prior art, and provides a micro-solid forming process and a micro-solid forming device, which have the advantages of liquid state and semi-solid state, can form castings with complex structures, improve the quality of the castings to a certain extent, improve the process yield, save the consumption of raw materials, and realize digital and intelligent control.

In order to achieve the technical purpose and achieve the technical effect, the invention is realized by the following technical scheme:

a micro-solid state molding process, comprising the steps of:

step 1) utilizing pressure to enable molten metal to flow from a heat preservation furnace to a model cavity through an intermediate pipeline;

step 2) controlling the pipe wall temperature of the intermediate pipeline so as to:

the temperature of the molten metal close to the central part of the middle pipeline is higher than the liquidus temperature of the molten metal, so that the molten metal is maintained in a liquid phase;

the temperature of the metal liquid close to the pipe wall part of the middle pipeline is lower than the liquidus temperature of the metal liquid, so that the metal liquid generates a solid phase and solidified dendritic crystals grow;

step 3) arranging a stirring device around the intermediate pipeline, stirring the molten metal in the molten metal when the molten metal flows through the intermediate pipeline, so that the grown solidified dendritic crystals are broken, refined and dispersed in the molten metal to form nucleation cores when the molten metal is solidified, and the nucleation cores after refining and dispersion distribution enable the molten metal to be in a micro-solid state with high fluidity;

and 4) continuously applying pressure to the micro-solid metal liquid to enable the metal liquid to flow into a mold cavity, stopping a gate of the mold cavity after the mold cavity is filled, finishing the pouring process, and removing the poured casting to prepare for pouring of the next mold.

Furthermore, the middle pipeline is a liquid lifting pipe, and the molten metal in the heat preservation furnace stably flows to the mold cavity from bottom to top through the liquid lifting pipe under the action of pressure.

Further, the temperature of the pipe wall of the intermediate pipeline and the temperature of the metal liquid in the heat preservation furnace are controlled, after stirring, the temperature range of the metal liquid is divided and controlled to seven levels of L0-L7 before entering a mold cavity, and an interval temperature delta t below a metal liquid phase line is used₀At a minimum temperature level L0, with each additional interval temperature Δ t₀In one grade, up to the L7 grade, each grade temperature corresponds to a different solid fraction and fluidity.

Further, the stirring device is an electromagnetic stirring device, and is used for rotationally stirring the molten metal in a manner of not contacting with the molten metal.

A micro-solid forming device comprises a heat preservation furnace, a liquid lifting pipe and a model cavity, wherein one end of the liquid lifting pipe is introduced into the heat preservation furnace, and the other end of the liquid lifting pipe is communicated to the bottom of the model cavity.

Furthermore, the top of the heat preservation furnace is provided with a furnace cover and a corresponding pressurizing opening, so that a sealed cavity is formed inside the heat preservation furnace, pressure is applied conveniently, and the lift pipe penetrates through the furnace cover from the top and is led into the heat preservation furnace.

Furthermore, an electromagnetic stirring device is arranged on the periphery of the lift pipe and used for stirring the molten metal flowing through the lift pipe in a non-contact manner.

Furthermore, the electromagnetic stirring device is arranged on the periphery of the riser pipe at the exposed part between the holding furnace and the mold cavity.

The invention has the beneficial effects that:

the invention makes the metal in the liquid state and the semi-solid state, carries out process treatment on the metal liquid, increases the nucleation core in the metal liquid, reduces the gas content in the metal liquid, refines crystal grains, improves the structure, reduces the heat conduction to a cavity, reduces the thermal deformation of a sand mold and a sand core, improves the dimensional precision of the casting, reduces the feeding amount, has the advantages of both liquid state and semi-solid state, can form a casting with a complex structure, can improve the quality of the casting to a certain extent, improves the process yield, saves the consumption of raw materials, and realizes digital and intelligent control.

Drawings

FIG. 1 is a block diagram of a micro-solid molding apparatus according to the present invention;

FIG. 2 is a schematic view showing the temperature distribution of molten metal in the intermediate pipe;

FIG. 3 is a schematic diagram illustrating the difference between the pouring temperature range of the micro-solid forming process of the present invention, which takes aluminum alloy liquid as an example, and the conventional casting and semi-solid casting;

FIG. 4 is a graph of dendrite growth in the intermediate pipe under normal conditions;

FIG. 5 is a diagram showing the growth of the dendrites after being broken up under stirring conditions according to the present invention.

The reference numbers in the figures illustrate: 1. the device comprises a heat preservation furnace 2, a liquid lifting pipe 3, a model cavity 4, a furnace cover 5, an electromagnetic stirring device 6 and a gate mechanism.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

A micro-solid state molding process, comprising the steps of:

step 1) utilizing pressure to enable molten metal to flow from a heat preservation furnace to a model cavity through an intermediate pipeline;

step 2) controlling the pipe wall temperature of the intermediate pipeline so as to:

as shown in FIG. 3, taking the aluminum alloy liquid as an example, when the temperature of the aluminum alloy liquid is controlled, the temperature Δ T is controlled₁At the traditional casting temperature and the semi-solid temperature delta T₂Taking this temperature interval as the micro-solid temperature DeltaT₁And the micro-solid temperature Delta T of the aluminum alloy liquid according to the change of the components of the elements₁Correspondingly adjusting to meet the following temperature control principle, wherein the temperature of the metal liquid close to the central part of the middle pipeline is higher than the liquidus temperature of the metal liquid, and the metal liquid is maintained in a liquid phase;

the temperature of the molten metal near the pipe wall of the intermediate pipe is lower than the liquidus temperature thereof, so that the molten metal is in a solid phase, as shown in fig. 4, a solidified dendrite is grown, and in this embodiment, the temperature of the molten metal is lower than the liquidus temperature T thereof within a certain distance in the intermediate pipe which is closer to the pipe wall₀；

Step 3) arranging a stirring device around the middle pipeline, stirring the molten metal in the molten metal when the molten metal flows through the middle pipeline, so that the grown solidified dendritic crystals are broken, refined and dispersed in the molten metal to form nucleation cores when the molten metal is solidified as shown in fig. 5, and the refined and dispersed nucleation cores enable the molten metal to be in a micro-solid state with high fluidity;

and 4) continuously applying pressure to the micro-solid metal liquid to enable the metal liquid to flow into a mold cavity, stopping a gate of the mold cavity after the mold cavity is filled, finishing the pouring process, and removing the poured casting to prepare for pouring of the next mold.

The middle pipeline is a liquid lifting pipe, and the molten metal in the heat preservation furnace stably flows to the mold cavity from bottom to top through the liquid lifting pipe under the action of pressure.

The pipe wall temperature of the intermediate pipeline and the temperature of the metal liquid in the heat preservation furnace are controlled, in the embodiment, taking aluminum alloy as an example, after stirring, before entering a model cavity, the temperature of the aluminum liquid can be controlled to seven levels of L0-L7, the temperature below the liquidus line of the aluminum liquid is 5 ℃ as the lowest temperature level L0, and one level is added when the temperature is increased by 5 ℃ until the temperature of L6 level is L6 level, each level of temperature corresponds to different solid fraction and fluidity, the lower the temperature, the higher the solid content, the better the casting structure and mechanical property, but the poor fluidity, and is not beneficial to forming complex castings, so that different levels can be selected according to the complexity and performance requirements of the casting structure, thereby realizing the forming of complex and thin-walled castings, the principle of selecting the temperature is that when the casting structure is relatively complex, the pouring temperature is relatively higher, and when the requirements on the structure and performance are higher, the selective casting temperature is relatively low, and the adaptability is very wide.

The stirring device is an electromagnetic stirring device and is used for rotationally stirring the molten metal in a mode of not contacting with the molten metal.

As shown in figure 1, the micro solid forming device comprises a heat preservation furnace 1, a liquid lifting pipe 2 and a model cavity 3, wherein one end of the liquid lifting pipe 2 is introduced into the heat preservation furnace 1, and the other end of the liquid lifting pipe is communicated to the bottom of the model cavity 3.

The top of the heat preservation furnace 1 is provided with a furnace cover 4 and a corresponding pressurizing opening, so that a sealed cavity is formed inside the heat preservation furnace 1 to apply pressure, and the lift pipe 2 penetrates through the furnace cover 4 from the top and is led into the heat preservation furnace 1.

The periphery of the lift tube 2 is provided with an electromagnetic stirring device 5 for contactless stirring of the molten metal flowing through the lift tube 2.

The electromagnetic stirring device 5 is arranged on the periphery of the riser pipe 2 at the exposed part between the holding furnace 1 and the model cavity 3, and in the embodiment, a gate mechanism 6 is further arranged on one side of the riser pipe 2 to control the opening and closing of the riser pipe 2, so that when pouring is completed, the gate mechanism is gated at a pouring gate.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.