JPH0428461A - Method for continuously casting semi-solidified metal and nozzle for pouring semi-solidified metal - Google Patents

Abstract

PURPOSE:To continuously produce perfectly solidified metal by rapidly solidifying semi-solidified metal with a continuous casting mold directly connected through a pouring nozzle providing an induction heating coil and an electric source for supplying electric power to discharging part in a cooled stirring vessel for producing the semi- solidified metal. CONSTITUTION:Molten metal is continuously supplied into a molten metal receiving vessel 1 and cooling and stirring action are given with cooling and high rotating velocity in the cooled stirring part 4a at tip part of stirrer in gap 3 between the stirring vessel 2 and the stirrer 4 in the stirring vessel 2 to produce the semi-solidified metal 12 and this flows down to the discharging vessel 5. This apparatus has structure supplying the semi-solidified metal into the continuous casting mold 7 from the discharging hole 5 through the pouring nozzle 6, and the proper electric power from the high frequency electric source in the pouring nozzle 6 is impressed to the induction heating coil 6b, and by suitably heating, formation of solidified shell is prevented. In the mold 7, the semi-solidified metal 12 is brought into contact with water cooled wall in the mold body 7a and rapidly cooled, and the solidified shell 12 is formed to make the cast billet 10 and the perfectly solidified cast billet is produced. By this method, the cast billet having uniform and good quality can be obtd.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention continuously casts a solid-liquid metal mixture (referred to as semi-solid metal for simplicity) in which non-dendritic primary crystals are dispersed in a metal melt. Developmental research on the method and equipment used to carry out this method, with the aim of further expanding the benefits of continuous casting by converting molten metal into a semi-solid state and then continuously casting this semi-solid metal. This is the result of

By reheating the continuous cast slab in this way to a temperature range of semi-solid state, its thixotropic property (having large deformability under small stress) is utilized for processing (hereinafter referred to as "thixo processing"). ), die-cast,
It is also used as a processed material for various processes such as closed forging, hot pressing, and vacuum forming.

(Prior Art) A method for continuously producing a material for Nisso processing by continuously casting a semi-solid metal is disclosed in Japanese Patent Publications No. 56-20944, Japanese Patent Publication No. 7148-1986, and the like. In these methods, a discharge nozzle is provided at the bottom of an apparatus for producing semi-solid metal, and the semi-solid metal discharged from the nozzle is supplied to the open mold of the prior art, or the apparatus for producing semi-solid metal is directly connected to a continuous casting mold. It is made to be.

However, implementation of these methods is technically difficult due to the unique characteristics of semi-solid metals, and they have not yet been put to practical use.

This is because the semi-solid metal violently stirs the molten metal (-alloy for boat fishing) while cooling it, and the branches of the dendritic primary crystals that are forming in the molten metal disappear or shrink. This is because it has been converted into a rounded form, has already released some latent heat, is a liquid that has begun to solidify, has no superheat, and has a very high apparent viscosity. In short, it has the drawbacks of very poor fluidity and easy condensation, so it is extremely difficult to discharge a constant amount from the nozzle, and even if it is directly connected to the mold, condensation has already started at the nozzle in front of the mold, and the mold It becomes impossible to pull out the pieces, and even in the mold, it exhibits characteristics different from conventional molten metal, so even if the heat load on the mold can be reduced, if the conventional continuous casting technology is used, It was difficult to put it into practical use.

(Problem to be Solved by the Invention) A semi-solid metal has already released some latent heat and solidified, and solidified crystals are dispersed in the molten metal.
It has the characteristics of having no superheat at all, so it is very easy to coagulate, has a high apparent viscosity, and has poor fluidity.

Therefore, it is difficult to continuously cast semi-solid metals using conventional continuous casting techniques.

The problems in that case are described below.

(1) In the conventional method of supplying semi-solid metal to an open mold for continuous casting through nozzle discharge from a semi-solid metal manufacturing apparatus, continuous quantitative supply is difficult because semi-solid metal has high apparent viscosity and poor fluidity.

(2) Characteristics of semi-solid metal (
(solid phase ratio, apparent viscosity, etc.) vary greatly, so maintaining a constant discharge amount is an absolutely necessary condition for stable operation in semi-solid metal manufacturing equipment.

(3) Therefore, it is preferable to directly connect the semi-solid metal production equipment and the continuous casting mold, but if the conventional technology is used, the semi-solid metal will adhere to the entrance of the mold and continuously cast slabs. It is impossible to pull it out.

(Means for solving the problem) (11 Directly connect the semi-solid metal manufacturing equipment and the continuous casting mold,
By keeping the rate of drawing slabs from the continuous casting mold (casting speed) constant, the amount of discharge from the semi-solid metal manufacturing equipment, that is, the amount of molten metal processed, is kept constant and semi-solid metal with stable properties is manufactured. .

(2) The discharge part of the semi-solid metal manufacturing apparatus and the continuous casting mold are connected by a nozzle part having an opening cross-sectional area sufficient to overcome the viscous resistance of the semi-solid metal to be manufactured and flow.

(3) A high-frequency induction heating coil is installed in the nozzle section and is constantly heated with electricity to prevent semi-solid metal passing through the nozzle section from adhering to the nozzle section.

(4) This high-frequency heating is applied to semi-solid metals flowing through it.
Although a large amount of heat is not applied, a large amount of heat is applied to the adhered metal, which remelts it and prevents it from joining with the mold shell.

In other words, this invention injects semi-solid metal obtained by stirring molten metal while cooling it into the discharge section of a cooling stirring tank through an injection nozzle equipped with an induction heating coil and a power source for supplying electric power to the coil. Continuous casting method for semi-solid metal (first invention) characterized by continuously producing slabs of quenched and solidified semi-solid metal using a continuous casting mold that is directly connected to the casting mold, and conductivity with excellent high-temperature strength The nozzle body is made of ceramic, and an induction heating coil is placed around the outer periphery of the nozzle body and power is supplied to it to maintain the nozzle body at a high temperature, thereby preventing the metal passing through the interior from condensing. A semi-solid metal injection nozzle (second invention) characterized by:

FIG. 1 shows an overall diagram of the configuration of an apparatus for carrying out the method of the present invention, and FIG. 2 shows a detailed diagram of an injection nozzle section for supplying hot water to a continuous casting mold.

In FIG. 1, the apparatus for manufacturing semi-solid metal is comprised of a receiving tank 1, a stirring tank 2, a stirring gap 3, a stirrer 4, and a discharge tank 5.

The molten metal receiving tank 1 is a cylindrical container lined with a refractory material, and a portion of the molten metal receiving tank 1 is provided with a molten metal receiving port 1'.

The stirring tank 2 has an inner surface that is kept warm or cooled, and provides a cooling stirring effect to the molten metal in the gap 3 between it and the stirrer 4 to produce semi-solid metal.

The stirrer 4 is composed of a cooling stirring part 4a at the tip and a drive shaft 4b, and has rotational drive and elevating means, and has a structure that allows it to rotate at high speed as shown by the arrow α, and to move up and down as shown by the arrow β. .

The discharge tank 5 is a heat-retainable container lined with a fireproof heat insulating material, and has a discharge port 5' horizontally provided at its bottom and an injection nozzle 6 attached thereto.

Next, the continuous casting device is composed of a mold 7, a spray cooling pipe 8, and a pinch roll 9, and is a device that continuously produces slabs 10 having a predetermined cross-sectional shape. Directly connected to manufacturing equipment.

In this example, a high frequency power source 11 is attached to the injection nozzle 6.

Here, regarding the structure of the injection nozzle 6 and the continuous casting mold 7,
This will be explained in detail with reference to FIG. The injection nozzle 6 is composed of a nozzle body 6a made of refractory ceramic, an induction heating coil 6b provided on its outer periphery, a brake ring 6c at the nozzle outlet, and a power supply terminal 6d, and is directly connected to the discharge tank 5.

The continuous casting mold 7 is composed of a pure copper mold body 7a with both ends open and having a predetermined slab cross-sectional shape, a water jacket 7b, a water supply pipe 7c, and a drain pipe 7c', through which a large amount of cooling water is passed. The mold body 7a is cooled and the semi-solid metal 12 supplied thereto is indirectly cooled and solidified by contact cooling, and is closely attached to the brake ring 6c of the hot water supply nozzle 6. A spray nozzle 8 is installed at the outlet of this mold 7.
The structure is such that cooling water is directly injected to further cool the slab 10.

(Function) Molten metal is continuously supplied to the inlet 1', and in the stirring tank 2, in the gap 3 between the stirring tank 2 and the stirring bar 4, cooling of the cooling stirring part 4a at the tip of the stirring bar and high speed rotation are performed. A semi-solid metal 12 is produced under strong cooling and stirring action.
It flows down into the discharge tank 5. The stirrer 4 can be moved up and down, and the gap 3 can be adjusted and attached/detached as required.

The semi-solid metal 12 produced here already has 10 to 50
% of latent heat of solidification and a solid phase is generated, and the temperature is lower than the liquidus temperature, but it is a slurry-like metal that has high viscosity and is extremely easy to solidify.

Therefore, if this semi-solid metal I2 is directly supplied to a conventional continuous casting mold, a strong solidified shell will be formed at the entrance of the mold, making it impossible to pull it out, making it difficult to put it into practical use.

Therefore, in this invention, the semi-solid metal 12 is supplied to the continuous casting mold 7 from the discharge port 5' through the injection nozzle 6, and the injection nozzle 6 is supplied with appropriate electric power from the high frequency power source 10 to the induction heating coil 6b. The formation of a coagulated shell is prevented by applying and heating appropriately. In this case, it is preferable to use a conductive ceramic having excellent high-temperature strength as the nozzle body 6a. Furthermore, brake ring 6C
is made of ceramic that does not get wet with molten metal.
The semi-solid metal 12 flows into the mold in a rectified state without adhering to the outlet of the injection nozzle 6.

In the mold 7, the semi-solid metal 12 is rapidly cooled by contacting the water-cooled wall of the mold body 7a, and a solidified shell 12' is quickly formed into a slab lO, which is continuously pulled out at a drawing speed corresponding to the amount of molten metal supplied. A fully solidified slab of semi-solid metal is produced by drawing as shown in γ.

In this case, in continuous casting of semi-solid metal, great features not found in conventional continuous casting methods are exhibited due to the characteristics of semi-solid metal. First, the thermal effect is that of releasing latent heat of solidification.
Due to the temperature conditions, the formation and growth of the solidified shell 12' is rapid, the heat load on the mold is small (and high-speed drawing is possible).

Secondly, since semi-solid metal is already in the form of a slurry with low temperature and high viscosity, it flows into the mold in a laminar (rectified) state, and the starting point of solidified shell formation is stable, which is different from the conventional method. Similarly, there is no break point of the solidified shell in the middle of the mold, and there is no risk of breakout.

Therefore, unlike conventional equipment, there is no need for intermittent drawing, and slabs with good surface quality can be manufactured with high productivity by continuous drawing. The next feature is that semi-solid metal has a small amount of solidification shrinkage, so there is no air gap, and there is less risk of deformation and cracking due to uneven cooling, making it possible to manufacture slabs with complex cross-sectional shapes. , it becomes possible to produce slabs that more closely resemble the final product shape.

(Example) Next, as an example, a case where the present invention is applied to an electromagnetic stirring type semi-solid metal manufacturing apparatus will be described with reference to FIG. 3. In FIG. 3, an electromagnetic stirring type semi-solid metal manufacturing apparatus is composed of a cooling cylinder 101 made of non-magnetic metal, a water jacket 102 that also serves as a coil case, and an electromagnetic stirring coil 103 that generates a rotating magnetic field. Water supply pipe 10
4 to forcefully cool the outer periphery of the cooling cylinder 101.
Water is drained from the upper drain pipe 105, and alternating current electricity is applied to the electromagnetic stirring coil 103 to apply rotational stirring force to the molten metal inside by means of a rotating magnetic field.

Next, the continuous casting apparatus includes a pure copper open mold body 111 having a predetermined casting cross-sectional shape and a water sink.

Cooling water 115 is passed through a water supply pipe 113 to forcibly cool the mold body 111, and is drained 115' from a drain pipe 114 to cool and cool the semi-solid metal 118 in the mold. The structure is such that a slab 119 is solidified and continuously pulled out using pinch rolls 116.

These semi-solid metal manufacturing devices and continuous casting molds are directly connected via a hot water supply nozzle 108. This hot water nozzle 10
No. 8 has an inner diameter large enough to flow and discharge highly viscous semi-solid metal, and has an induction heating coil 109 built-in. The solidified metal 118 is appropriately heated to prevent the semi-solid metal 118 passing through from solidifying and growing.

Here, molten metal is continuously supplied into the cooling cylinder 101,
The electromagnetic stirring coil 103 is energized, and the semi-solid metal 118 is produced by contacting and cooling the cooling cylinder 101 while being rotated and stirred by a rotating magnetic field. This semi-solid metal 118 is introduced into the continuous casting mold 111 while being induction heated by the injection nozzle 108 section, cooled and solidified to form a slab 119, and is continuously moved by the pinch rolls 116 at a rate commensurate with the supply amount of the molten metal 117. The semi-solid metal is then drawn to produce slabs of semi-solid metal.

As described above, the present invention is a method and apparatus that can be applied to any semi-solid metal manufacturing apparatus and any continuous casting machine, and conventional techniques can be applied as is to operating methods such as starting the continuous casting machine.

(Effects of the Invention) (1) Completely solidified slabs of semi-solid metal can be manufactured continuously. This slab can also be used as a processing material utilizing thixotropy by reheating it to a temperature range of a semi-solidified state.

(2) The cast slab has no dendrite structure, is homogeneous, and has better quality than conventional continuously cast slabs.

(3) It becomes possible to manufacture slabs with a cross-sectional shape similar to that of the final product, and process saving becomes possible. It is particularly advantageous for processing difficult-to-process materials.

(4) The heat load on the mold is reduced, and an improvement in mold life can be expected.

(5) There is no need for intermittent drawing, which is a disadvantage of direct continuous casting,
Continuous drawing can be expected to improve production and surface quality.

(6) There is no risk of breakout accidents.

[Brief explanation of drawings]

Fig. 1 is an overall view showing the basic configuration of an apparatus for carrying out the method of the present invention, Fig. 2 is a detailed view of its injection nozzle section, and Fig. 3 is an overall view showing one of the application examples. be. 1... Hot water receiving tank 1'... Hot water receiving port 2...
Stirring tank 3... Stirring gap 410. stirring bar
5... Discharge tank 6... Injection nozzle
7... Continuous casting mold 8... Spray nozzle 9.
... Pinch roll 11 ... High frequency power supply 101
... Cooling cylinder 102 ... Water jacket that also serves as a coil case 103 ... Electromagnetic stirring coil 104 ... Water supply pipe 105 ... Drain pipe 108 ... Hot water supply nozzle 109 ... Induction heating coil 110 ...・High frequency power supply 111... Continuous casting mold 112... Water jacket 116... Pinch roll Fig. 1 α Fig. 2

Claims (1)

[Claims] 1. The semi-solid metal obtained by stirring molten metal while cooling is provided with an induction heating coil and a power source for supplying power to the coil at the discharge part of the cooling stirring tank. A continuous casting method for semi-solid metal, characterized by continuously producing slabs of rapidly cooled and solidified semi-solid metal using a continuous casting mold directly connected to an injection nozzle. 2. The nozzle body is made of conductive ceramic with excellent high-temperature strength, and an induction heating coil is placed around the outer periphery of the nozzle body and power is supplied to it to maintain the nozzle body at a high temperature. A semi-solid metal injection nozzle characterized by preventing condensation of the metal passing through it.