JPH0732113A - Die casting method of rheometal - Google Patents

Abstract

PURPOSE:To reduce the energy required for reheating, to reduce a cost and to improve productivity and workability by putting a rheometal produced by a rheomaker into a preheated heat shielding container, tilting this container and charging the container into the sleeve of a die casting machine. CONSTITUTION:The inside wall surface of a container 8 made of heat resistant high-density ceramics has a draft angle toward an opening. The container 8 is covered with a heat insulating material 9. The preheated container 8 is placed below the discharge port of the rheomaker and the rheometal is transferred into the container 8. The rheometal is immediately transferred and the container 8 is tilted to charge the rheometal into the sleeve of the vertical type die casting machine. As a result, the direct injection molding of the rheometal is possible and the energy required for the reheating is reduced. The need for a high-frequency induction heating device, ceramic sleeve, etc., is eliminated. The cost is thus reduced and the productivity and workability are improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention proposes a die-casting method for a suitable solid-liquid coexistence region metal.

When the molten metal is cooled to a solid-liquid coexisting region while being stirred, the solid phase that has crystallized becomes granular due to the effect of stirring, and becomes a state of being uniformly dispersed and suspended in the liquid phase. Since such a material in the solid-liquid coexistence region has the same fluidity as a liquid, it can be easily injection-molded.

Here, the material in the solid-liquid coexistence region is called rheometal. Further, a device for producing a rheometal while stirring a molten metal is called a rheomaker, and a method for feeding a rheometal into a die casting machine sleeve and injecting it into a die to form a product shape, that is, a rheometal die casting method is called a rheocast method.

In this rheocasting method, the latent heat of solidification of the material is small and a part of it solidifies and is uniformly dispersed, so that a heat load on the mold is small and a product having a uniform metal structure can be obtained. It has the advantage that it can.

[0005]

2. Description of the Related Art In the conventional die-casting method for molten metal, the molten metal is high in temperature and has large latent heat of solidification, so that the heat load on the mold is large, and the injected molten metal is cooled and solidifies from the portion in contact with the mold. It has drawbacks such as a non-uniform structure in which the metal structures of the surface layer portion and the inside are different.

On the other hand, in the rheocast method, in which the heat load on the die is less than that in the die casting method for molten metal and a product having a uniform metal structure is obtained, the same method as in the case of die casting method for ordinary molten metal is used. When the method is used to scoop out rheometal with a dipper and load it into the injection sleeve, there is a problem that the rheometal solidifies in the dipper, and this method cannot die-cast.
Therefore, in order to avoid the above problem, a method in which the rheometal is once cooled and solidified to room temperature to form a lump, and the lump material is charged into a sleeve and then reheated to a solid-liquid coexisting region by using high frequency induction heating or the like, and injection molding is performed. Was used.

However, this method requires energy for reheating and the equipment therefor, and particularly when high frequency induction heating is performed in the sleeve, the sleeve uses a fragile ceramic which has a short life and impairs workability. However, there are problems such as increased cost, impaired productivity and workability.

[0008]

The present invention advantageously solves the above-mentioned problems, and directly injection-molds a rheometal produced by a rheomaker without once cooling and solidifying the product, product quality, economic efficiency and productivity. The purpose of the present invention is to propose a die-casting method for excellent rheometal.

[0009]

The summary of the present invention is as follows. After transferring the rheometal manufactured by Leomaker into a preheated heat-shielding container, transfer it onto a die casting machine sleeve, tilt the container, insert into the sleeve and perform injection molding. It is a die-casting method of Leo metal. In the item, a heat-shielding container coated with a heat insulating material is used. In paragraph (1) or (2), a heat-shielding container having a draft gradient toward the opening is used. The term, the term, or the term uses a heat-shielding container having a movable bottom lid. In the item (1), the heat-shielding container into which the rheometal has been transferred is held in the soaking furnace until the rheometal is loaded into the sleeve.

[0010]

The background of the invention and its operation will be described. If it is possible to solve the problem that the rheometal solidifies in the ladle from the time it is transferred to the ladle to the time it is loaded in the die casting machine sleeve, the problem that the heat load of the die in the die casting of the molten metal is large as described above. It is possible to solve all the problems that the metal structure of the product becomes non-uniform and that the rheometal is once cooled and solidified to room temperature and then reheated.

Normally, in the molten metal die casting method, the molten metal is scooped out, charged into a sleeve, and injected into a mold.
The temperature of the molten metal decreases due to heat removal from the ladle and heat radiation from the time when the molten metal is pumped out to the time when the molten metal is charged into the sleeve.
However, in this case, the temperature of the molten metal is raised to a temperature that allows for this decrease in advance, thereby preventing the molten metal from solidifying in the ladle. Following this, if the temperature of the rheometal is increased by the rheocast method, the solid phase particles are dissolved and the characteristics of the rheocast method are lost.

Therefore, the present invention uses a heat-shielding container which has been preheated to a temperature substantially equal to the temperature of the rheometal in advance, and transfers the rheometal manufactured by a Rheomaker into this container to solidify the rheometal in the container. By doing so, it becomes easy to load the rheometal from the container into the sleeve, and good die casting can be performed.

In this heat-insulating container, a porous refractory made of hardened ceramic fibers which is a heat resistant material, or a high density ceramic such as Si ₃ N ₄ -20% BN which is a heat conductive material or stainless steel is used. It is possible to use a metal of which a heat insulating material is coated.

[0014] By making the container heat-shielding in this way, even when the container containing the rheometal is held in the soaking furnace, the transfer from the Leo maker to the soaking furnace and from the soaking furnace to the die casting machine are made. It is necessary to prevent solidification of the rheometal due to heat dissipation during the transfer.

On the other hand, the rheometal becomes stationary in the container and the solid phase particles are connected to each other to form a jelly. The solid-phase particles are weakly connected to each other, and at the time of injection, the connection is broken by the injection pressure when passing through the gate, so that the solid-phase particles are isolated in the liquid and behave like a liquid as a whole. Become. However, the jelly-like rheometal has the strength to withstand its own weight, and even if the container is tilted, it does not drop from the container, and the problem that the rheometal cannot be loaded into the sleeve occurs.

In order to prevent this trouble, it is sufficient to use a container having a draft toward the opening as shown in FIG. 2, and by tilting the container, the rheometal can be easily dropped by its own weight. . Further, as shown in FIG. 3, it is also possible to use a container having a movable bottom lid, and if this is tilted and the bottom lid is directed toward the opening and pushed by a pushing rod, the rheometal can be surely discharged from the container. You can

In some cases, the rheometal must be held and held for a long time due to the practical process. In this case, by holding the rheometal together with the container in the soaking furnace, the solidification of the rheometal can be prevented for a long time, and the time until die casting can be adjusted.

As described above, the preheated heat-shielding container can prevent the solidification of the rheometal from the time when the rheometal is transferred from the rheomaker to the time when the rheometal is charged into the sleeve of the die casting machine. The use of a container with a draft or a container with a movable bottom lid facilitates and ensures charging of the rheometal from the container to the sleeve.
Further, when the rheometal cannot be injection-molded immediately after the production because of the process, the solidification of the rheometal is prevented by holding the container into which the rheometal has been transferred in the soaking furnace. Thus, good die casting can be performed without once cooling and solidifying the rheometal produced by the rheomaker.

[0019]

[Examples] Solid fraction produced by Rheomaker shown in Fig. 1:
Using Rheometal of Al alloy (AC4C) of 0.4 (temperature: 573 ° C), die casting was attempted by a method conforming to the present invention (conforming example) and a method not conforming (comparative example),
The metal structure of the die cast product obtained was investigated along with the investigation of the situation.

As a conventional example, die casting was performed using a molten Al alloy (AC4C), and the metal structure of the obtained die cast product was investigated. Here, FIG. 1 is an explanatory diagram of a Leo maker. In the figure, 1 is an agitator rotating shaft connected to a drive system, 2 is a receiving tank for receiving the molten metal, 3 is an agitator having a thread groove on the surface for facilitating discharge of rheometal, 4 is agitating the molten metal A cooling tank for cooling the solid coexistence region while stirring with the child 3, 5 is a water cooling jacket of the cooling tank, 6 is a slide valve for controlling the discharge amount of rheometal, and 7 is a discharge port for rheometal.

The heat-shielding container used in this embodiment is shown in FIGS. 2 and 3. FIG. 2 is an explanatory view of a heat-shielding container having a draft angle toward the opening. In this figure, 8
Is a container made of heat-resistant high-density ceramics (Si ₃ N ₄ -20% BN), and the inner wall surface of the container has a draft gradient toward the opening. Further, 9 is a heat insulating material (mullite wool) for covering the container 8.

FIG. 3 is an explanatory view of a heat shield container having a movable bottom cover. In this figure, the heat-resistant high-density ceramics _{(Si 3 N 4 -20% BN} ) made of cylindrical side wall 10, the coating heat insulating material (mullite wool) 11, 12 covering the heat insulating material of the bottom (mullite wool ), 13 is a movable bottom lid made of heat resistant high density ceramics (Si ₃ N ₄ -20% BN), and 14 is a rod (made of metal) for extruding the bottom lid. In addition, this stick 14
Does not fix to the bottom lid 13 and is detachable because it interferes with the holding of the container containing the rheometal in the soaking furnace.
Further, a wire (not shown) is attached to the bottom lid 13 to prevent the bottom lid 13 from being discharged and dropped together with the rheometal when the rhometal is discharged by pushing the bottom lid 13 with the rod 14.

The processing conditions and investigation results for the conforming example, the comparative example and the conventional example will be described below in order.

Application Example 1 A container shown in FIG. 2 preheated to a temperature of 600 ° C. is placed below the discharge port 7, and rheometal (solid phase ratio: 0.4,
(Temperature: 573 ° C) was transferred, immediately transferred, the container was tilted, and rheometal was loaded into the sleeve of the vertical die casting machine and injected. As a result, the rheometal could be loaded into the sleeve without any problem, and normal injection could be performed. A product having a uniform metal structure and soundness was obtained.

FIG. 4 shows a photograph of the metal structure of the product obtained by this conforming example 1. As is clear from this figure, a metallic structure in which granular primary crystals are uniformly dispersed in both the surface layer and the inside is obtained.

Conformity example 2 The container shown in FIG. 3 preheated to a temperature of 600 ° C. is placed below the discharge port 7, and rheometal (solid phase ratio: 0.4,
(Temperature: 573 ° C.) was transferred, immediately transferred, the container was tilted, the bottom lid 13 was extruded by the rod 14, and rheometal was loaded into the sleeve of the vertical die casting machine and injected. The bottom lid 13 was prevented from falling into the sleeve together with the rheometal by the wire attached to the bottom lid 13. As a result, the rheometal could be loaded into the sleeve without any problem, and normal injection could be performed. A product having a uniform metal structure and soundness was obtained.

Conformance Example 3 The container shown in FIG. 2 preheated to a temperature of 600 ° C. is placed below the outlet 7, and rheometal (solid phase ratio: 0.4,
(Temperature: 573 ° C.) was transferred, the container was held in a soaking furnace heated to 582 ° C. for 10 minutes, then transferred, and the container was tilted and charged with rheometal into the sleeve of the vertical die casting machine and injected. As a result, the rheometal could be loaded into the sleeve without any problem, and normal injection could be performed. A product having a uniform metal structure and soundness was obtained.

Comparative Example 1 An iron dipper preheated to a temperature of 600 ° C. was placed below the discharge port 7, and rheometal (solid phase ratio: 0.4
, Temperature: 573 ℃), immediately transferred, tilting the dipper to load the rheometal into the sleeve of the vertical die casting machine, but the rheometal solidified in the dipper and could not be loaded.

COMPARATIVE EXAMPLE 2 The container shown in FIG. 2 at room temperature was placed below the outlet 7 and the container was filled with rheometal (solid phase ratio: 0.4, temperature: 573).
(° C.) Was injected, immediately transferred, and the container was tilted to load the rheometal into the sleeve of the vertical die casting machine, but the rheometal solidified in the container and could not be loaded.

Comparative Example 3 A container shown in FIG. 2 preheated to a temperature of 600 ° C. was placed below the discharge port 7, and rheometal (solid phase ratio: 0.4,
(Temperature: 573 ℃) was transferred and kept in the atmosphere for 10 minutes, then the container was tilted to load the rheometal into the sleeve of the vertical die casting machine, but the rheometal solidified in the container and could not be loaded. It was

Comparative Example 4 A container 8 from which the heat insulating material 9 shown in FIG. 2 preheated to a temperature of 600 ° C. has been removed is placed below the discharge port 7, and the container 8 is filled with rheometal (solid phase ratio: 0.4, temperature: : 573 ° C.) and immediately transferred, the container was tilted to load the rheometal into the sleeve of the vertical die casting machine, but the rheometal solidified in the inner wall 8 of the container and could not be loaded.

Conventional example: Al alloy CAC4 alloy similar to that used in the above-mentioned conforming example and comparative example, liquidus temperature: 607 ° C), melted at a temperature of 710 ° C was pumped with an iron dipper preheated to a temperature of 600 ° C. Then, it was immediately transferred, the dipper was tilted, and the molten metal was injected into the sleeve of the vertical die casting machine and injected. I made a normal injection,
The metallurgical structure of the obtained product was non-uniform. A photograph of the metal structure of the product obtained by this conventional example is shown in FIG. As is clear from this figure, the surface layer and the inside have different structures. That is, a primary crystal with a relatively small amount of Si is observed in the surface layer portion, and a large eutectic crystal with a large amount of Si (black portion) is observed inside.

[0033]

Industrial Applicability According to the present invention, a rheo metal manufactured by a Leo maker is first transferred to a preheated heat-shielding container, then transferred to the die casting machine sleeve, and the container is tilted and charged into the sleeve. According to the present invention, a rheometal produced by a rheomaker is used without using a conventional method such as once solidifying by cooling.
It can be directly injection-molded, the energy required for reheating can be reduced, a high-frequency induction heating device, a ceramic sleeve, etc. can be eliminated, and cost can be reduced and productivity and workability can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a Leo maker.

FIG. 2 is an explanatory diagram of a heat-shielding container having a draft angle toward the opening.

FIG. 3 is an explanatory view of a heat-shielding container having a movable bottom cover.

FIG. 4 is a metallographic photograph of the product obtained in conformance example 1.

FIG. 5 is a metallographic photograph of a product obtained by a conventional example.

[Explanation of symbols]

 1 Stirrer Rotating Shaft 2 Hot Water Tank 3 Stirrer 4 Cooling Tank 5 Cooling Jacket 6 Slide Valve 7 Discharge Port 8 Container 9 Heat Insulation Material 10 Cylindrical Side Wall 11 Heat Insulation Material 12 Heat Insulation Material 13 Bottom Lid 14 Bar

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Uchimura 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Stock company Rheotech (72) Inventor Kazunori Hironaka 1 Kawasaki-cho, Chuo-ku, Chiba Chiba Prefecture Stock Association (72) Inventor Hiroyoshi Takahashi 1st Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Stock company Reotech

Claims (5)

[Claims] 1. A rheo metal manufactured by a Leo maker is first transferred into a preheated heat-shielding container, then transferred onto a die casting machine sleeve, tilted, and inserted into the sleeve for injection molding. A rheometal die casting method characterized by: 2. The rheometal die-casting method according to claim 1, wherein a heat-shielding container coated with a heat insulating material is used. 3. The rheometal die-casting method according to claim 1, wherein a heat-shielding container having a draft gradient toward the opening is used. 4. The rheometal die-casting method according to claim 1, wherein a heat-shielding container having a movable bottom lid is used. 5. The die-casting method for a rheometal according to claim 1, wherein the heat-shielding container into which the rheometal has been transferred is held in the soaking furnace until the rheometal is loaded into the sleeve.