JPH0289540A - Method and apparatus for manufacturing semi-solidified metal - Google Patents

Abstract

PURPOSE:To obtain high quality semi-solidified metal by forming a cooling stirring vessel composed of tapered annular gap, rotating a cooling stirrer as controllable to vertical movement and maintaining and controlling this gap to the suitable min. CONSTITUTION:Molten metal supplied 1' into the stirring vessel 1 under holding condition to the fixed temp. beforehand through refining, is charged into the tapered annular gap 13 between the vessel 1 and the cooling stirrer 4. Then, intense cooling together with vigorous stirring effect are given to the molten metal in the gap 13 with the rotated stirrer 4 to make the semi-solidified state, and this is continuously discharged 19 from a discharged nozzle 3 and slide gate valve 3' at the bottom part. During this, the molten metal is directly brought into contact with pure copper cooling plate of the stirrer 4 and forcedly cooled. Therefore, solidified shell is formed on the plate and the gap 13 is made to narrow, but as the stirrer 4 is optionally possible to lift with hydraulic cylinder 10 for lifting and the position of the stirrer 4 can be controlled so as to maintain the suitable min. gap.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a method for producing 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. and manufacturing equipment.

(Prior art) As disclosed in Japanese Patent Publication No. 56-20944, an apparatus for continuously producing semi-solid metal is used to maintain molten metal supplied to a heat-retaining tank at a constant temperature while producing a cylindrical metal. The metal is introduced into the gap between the stirrer rotating at high speed in the cooling stirring tank, and is subjected to appropriate cooling and intense stirring to become a semi-solid state, which is then continuously discharged as semi-solid metal from a nozzle at the bottom. be.

This semi-solid metal is produced by vigorously stirring a molten metal (generally an alloy) while cooling it to transform the dendrites that are forming in the molten metal into a rounded form with the branches disappearing or shrinking. formed by. The finer the particles of non-dendritic primary crystals in semi-solid metals are, the better their properties are. Therefore, in the production of semi-solid metals, ■ a strong cooling effect that can increase the cooling rate as much as possible ■ dendrites, Two conditions are essential: a strong stirring effect to the extent that the branches disappear or shrink and are converted into a rounded non-wooden product. Semi-solid metal manufacturing techniques still have various drawbacks.

(Problems to be Solved by the Invention) The device disclosed in Japanese Patent Publication No. 56-20944 had major problems in terms of performance and structure, and was not a very practical device. In other words, the specific problems are as follows.

(1) Due to the structure, indirect cooling is performed from the refractory wall, so strong cooling means cannot be used, and the cooling rate is at most 1° C./sec or less, which not only makes it impossible to produce products with satisfactory quality, but also has low production capacity.

(2) Even if strong cooling is carried out with such a structure, it is difficult to start operation due to the formation of a solidified shell, and stable operation cannot be expected. The reason for this is that even during operation, the solidified shell thickness fluctuates and the gap changes, so the stirring effect is not stable and there is always a significant disadvantage of operation stoppage due to solidification.

(3) Regarding the structure of the device, there is a heating tank directly above the cooling stirring tank, and the drive shaft of the stirrer always penetrates the layer of molten metal, making it difficult to design a practical device, and from the viewpoint of strength. It cannot be rotated at very high speeds and cannot be used especially for high melting point metals.

(4) It is desirable to cool the stirrer from the viewpoint of cooling effect and stirring effect, but water cooling is dangerous and cannot be carried out.

(Means for Solving the Problems) This invention solves all of the above-mentioned problems with the following configuration.

In other words, this invention is an inverted convex conical body which forms a tapered annular gap between the inner surface of the stirring tank and the inner surface of the stirring tank as a cooling stirring zone, in a stirring tank which has a mortar shape with a hole in the bottom and is heated by an external heating means. The raw molten metal is introduced into the stirring tank while rotating a cooling stirrer that can be adjusted up and down along the center axis of the cone, and a mixed phase of non-dendritic crystals and molten material is produced in the cooling stirring zone. A method for producing a semi-solid metal (first invention), characterized in that the semi-solid metal is continuously taken out through a bottom hole of a stirring tank, and between a mortar-shaped stirring tank having a bottom hole opening and an inner surface of the stirring tank. The stirring tank is equipped with a cooling stirrer that forms a tapered annular gap, a means for driving the rotation of the cooling stirrer, and a means for adjusting the elevation. on the other hand,
A semi-solid metal manufacturing apparatus (second invention) characterized in that the cooling stirrer has a strong cooling means that fills a tapered annular gap between the inner surface of the stirring tank and the cooling stirring zone, and an inverted mushroom-shaped shaft thereof. A core body having a vertical through hole in the handle, and a large number of radial horizontal holes that are opened in two rows above and below on the outer periphery of the expanded truncated conical head, which are connected to the vertical through hole, and cooling that spans between the rows of the radial horizontal holes. The highly heat-conductive conical outer shell is covered and fixed over the enlarged head of the core, leaving a medium path, and the base end, which fits into the open end of the vertical through-hole of the core, communicates with the lower row of radial horizontal holes. Consisting of a separation tube for the cooling medium passage, which extends into a vertical through-hole with a hole and forms a concentric double tube with the stem, and a protective refractory covering the core at the top and bottom of the enlarged head, respectively. This is a semi-solid metal cooling stirrer (third invention) characterized by the following.

Here, the cooling stirring zone formed by the stirring tank and the cooling stirring bar forms a tapered annular shape, and by controlling the position of the cooling stirring bar by raising and lowering it up and down, the taper annular gap of the cooling stirring zone is controlled to achieve an appropriate minimum gap. Since an effective stirring effect is provided in the stirrer, the rotational speed of the stirrer can be suppressed.

Since cooling stirring is possible even at relatively low speed rotation, there is no need for a heat insulating tank directly above the stirring tank as in the prior art, and the molten metal maintained at a constant temperature can be directly received into the cooling stirring tank.

Therefore, the drive shaft of the stirrer does not penetrate the molten metal, making the design easier in terms of structure and strength. However, by making the cooling stirrer a water-cooled structure and performing strong cooling from the stirrer side, both cooling and stirring effects can be achieved. Become excellent.

On the other hand, since cooling is not required on the stirring tank side, temperature control is facilitated by installing an induction heating coil to enable heating for heat retention even in the cooling stirring zone.

Now, the specific structure of this invention will be explained with reference to FIGS. 1 and 2. In FIG. 1, the stirring tank 1 has an inverted truncated cone shape, that is, a mortar shape with a hole in the bottom, and has a molten metal receiving port 1' at the upper end and a discharge nozzle 3 at the bottom as a bottom hole. Each has its own.

An induction heating coil 2 is provided around the outer periphery of the stirring tank 1, and by supplying electric power 16, it is possible to heat the molten metal inside. Since the induction heating coil 2 is an internal water-cooled type made of a hollow steel pipe, it has a certain degree of cooling effect by adjusting the power supply 16.

A slide gate valve 3' is provided to the discharge nozzle 3 at the bottom of the stirring tank 1 to control the discharge amount of the semi-solid metal 19.

On the other hand, a cooling stirrer 4 having an outer surface of an inverted cone corresponding to the inner surface of the stirring tank 1 is installed at the center of the stirring tank 1, and this cooling stirrer 4 is connected to an electric motor via a large gear 5, a small gear 6, and a torque detector 8 and rotates at a constant speed in the direction of arrow 12.

These rotary drive means are installed in the gear box 9' and the support frame 9, and have an integral structure including the cooling stirrer 4, and are supplied with hydraulic oil 1 by a hydraulic cylinder 10 connected to the support frame 9.
By operating 5, it is possible to move up and down as indicated by the double-headed arrow 17.

The cooling stirrer 4 has a cold water structure, has a rotary joint 11 at the end of its shaft, and allows cooling water 14 to pass therethrough, thereby serving to strongly cool the molten metal.

The water cooling structure of the stirrer 4 is illustrated in detail in FIG.

The cooling stirrer 4 mainly includes a core body 41 made of stainless steel, for example, and shaped like an inverted valve, the stem of which also serves as a drive shaft. The core body 41 has a vertical through hole 41' in the shaft handle, which communicates with a large number of horizontal holes in the radial direction that open in two stages, upper and lower, on the outer periphery of the enlarged truncated conical head. Established as The lower end opening of the vertical through-hole 41' is supported by a water supply block 44 integrally constructed with a separating pipe for the coolant passage serving as a water supply pipe 45.

A highly heat conductive conical shell shell made of, for example, pure copper and having a large number of axial cooling grooves 46' on its inner surface is attached as a cooling plate 46 to the outer periphery of the enlarged head of the core body 41 by, for example, diffusion welding. Although this cooling plate 46 may have an integral structure of a conical shell, it is considered that it is better to form the cooling plate 46 in the form of several segments divided in the circumferential direction, since thermal deformation can be prevented.

For example, a protrusion such as a screw foot 48 is provided at the lower end of the water supply block 44, and a ceramic tip block 47 is attached to this protrusion to cover the lower end of the core body 41, and a ceramic tip block 47 is attached to the protrusion at the lower end of the water supply block 44 to cover the lower end of the core body 41. A protective refractory is made by coating several layers of 49 and 7.

The cooling water flows through the water supply pipe 45 and the water supply block 4 as shown by the arrow 14.
4 and the water supply hole 42 to the cooling groove 46' of the cooling plate 46.
After cooling the cooling plate 46, the water passes through the drainage hole 43 and is drained to the upper part.

With this structure, the cooling stirrer 4 is sufficiently safe in terms of structure and strength, and can provide an effective cooling stirring effect to the molten metal introduced into the stirring tank.

(Function) The raw material molten metal 18 is previously refined and maintained at a constant temperature before being supplied into the stirring tank from the inlet 1'. The molten metal is strongly cooled by the rotating cooling stirrer 4 in the tapered annular gap 13 between the stirring tank 1 and the cooling stirrer 4 with a strong stirring effect, and becomes a semi-solid state, and is then discharged from the discharge nozzle 3 at the bottom. The metal is continuously discharged as semi-solid metal from the slide gate valve 3' as shown by arrow 19.

When starting operation, the cooling stirrer 4 is first retracted upward, a predetermined amount of molten metal 18 is received into the stirring tank 1 with the slide gate valve 3' closed, and the induction heating coil 2 is energized. heat it and maintain it at a constant temperature. Thereafter, the cooling stirrer 4 is rotated and lowered, and when it reaches a predetermined position while providing a cooling stirring effect, the operation is started. Therefore, it is extremely easy to start operation without worrying about initial solidification.

The molten metal is strongly cooled by directly contacting the pure copper cooling plate 46 of the cooling stirrer 4. Therefore, a solidified shell is formed on the cooling plate 46, the gap 13 becomes smaller, and there is a tendency for overload.
Since the cooling stirrer 4 can be moved up and down arbitrarily, the position of the cooling stirrer 4 is controlled so that an appropriate minimum gap is maintained.

In this case, position control is easily achieved by detecting variations in the load torque using the torque detector 7 and controlling the load torque to be as constant as possible. Also, the temperature during operation,
Even in response to changes in cooling conditions, by adjusting the electric power 16 supplied to the induction heating coil 2, everything from heating to cooling can be performed, temperature control is possible, accidents can be prevented, and stable operation can be achieved.

(Example) (Effect of the invention) The following effects are expected from this invention.

(1) By forming a cooling stirring zone consisting of a tapered annular gap and controlling the cooling stirrer up and down, it is possible to maintain and control the gap to an appropriate minimum and produce semi-solid metal, resulting in relatively low rotation speed. A sufficient stirring effect can be obtained even at this speed, and there is no danger of gas entrainment.

(2) Since the drive shaft of the cooling stirrer does not penetrate the molten metal layer, the cooling stirrer can be designed with sufficient practical structure and strength, and is particularly suitable for high-melting point metals.

(3) The molten metal can be strongly cooled by using a water-cooling structure on the cooling stirrer side.In particular, if the stirrer cooling structure according to the third invention is adopted, cooling strength comparable to that of the mold of a continuous casting machine can be obtained, and the appropriate minimum By operating in a gap, a cooling rate of 10° C./sec or more can be expected, and high quality semi-solid metal can be produced.

(4) An induction heating coil can be installed on the stirring tank side,
In the cooling stirring zone, it is possible to control the temperature by combining heating and cooling, and stable operation is possible.

[Brief explanation of drawings]

FIG. 1 is an overall explanatory diagram showing a specific configuration of the present invention, and FIG. 2 is a detailed sectional view showing a water cooling structure of a stirrer. 1... Stirring tank 1'... Inlet 2...
・Induction heating coil 3...Bottom hole 3'...Slide gate valve 4...Cooling stirrer 8...Electric motor 10...Hydraulic cylinder for lifting 41...Core patent applicant Rheotech Co., Ltd.

Claims (1)

[Scope of Claims] 1. A tapered annular gap is formed as a cooling stirring zone between the inside of the stirring tank and the inner surface of the stirring tank, which has a mortar shape with a hole in the bottom and is heated from the outside. While rotating the cooling stirrer, which is made of an inverted convex cone and can be adjusted up and down along the center axis of the cone, raw molten metal is introduced into the stirring tank, and the non-dendritic crystals produced in the cooling stirring zone are molten. A method for producing semi-solid metal, characterized by continuously taking out the solid mixed phase through the bottom hole of a stirring tank. 2. A mortar-shaped stirring tank having a bottom hole opening, a cooling stirrer forming a tapered annular gap between the inner surface of the stirring tank, a rotation driving means for the cooling stirrer, and a lifting adjustment operation means. The stirring tank has an external heating means for keeping the raw molten metal introduced into the tank warm, while the cooling stirrer has a strong cooling means that fills the tapered annular gap with the inner surface of the stirring tank as a cooling stirring zone. A semi-solid metal manufacturing apparatus characterized by having: 3. A core body that is shaped like an inverted mushroom and has a vertical through hole in its stem, along with a large number of radial horizontal holes that communicate with this hole and open in two rows, upper and lower, on the outer periphery of the enlarged truncated conical head. , a highly heat-conductive conical shell outer shell that covers and adheres to the enlarged head of the core, leaving a cooling medium path between the rows of radial horizontal holes, and a blocking end that fits into the open end of the vertical through-hole of the core. At the top and bottom of the separate tube and enlarged head of the cooling medium passage, respectively, the cooling medium passage has a communication hole communicating with the lower row of radial horizontal holes, and extends into the vertical through hole and forms a concentric double tube with the shaft stem. A cooling stirrer made of semi-solid metal, characterized in that it consists of a protective refractory covering a core.