JP2008511443A - Semi-solid metal slurry manufacturing apparatus and manufacturing method - Google Patents

Abstract

A crucible for preparing a semi-solid slurry having a liquid phase and a solid phase. The crucible includes a side wall provided with a lower end, a closing plate that can be engaged with and spaced from the lower end of the side wall, and a clamping means that contacts the lower end of the side wall and holds the closing plate. Moreover, the method of preparing a semi-solidified slurry is shown. The method includes providing a crucible having a side wall with a lower end and a closing plate, and contacting the lower end of the side wall and holding the closing plate. Next, the crucible is filled with the molten metal and the molten metal is cooled to form a semi-solid slurry. Finally, the lower end of the side wall is released from contact with the closing plate and the semi-solid slurry is moved from the side wall to the casting apparatus.

Description

  The present invention relates to the casting of semi-solid slurries (or semi-molten slurries) of molten metal, especially aluminum and aluminum alloys. More particularly, it relates to an apparatus for obtaining a semi-solid slurry and the use of a “slurry on demand” method to obtain such a slurry.

  Casting of semi-solid slurry of molten metal has been carried out for many years. Many methods for casting such slurries are known in the art. These methods generally include a pre-prepared and adjusted step of reheating the solidified ingot to a semi-solid state and then transferring the resulting slurry to a casting mold.

  However, in recent years, a casting method for obtaining a semi-solid slurry by controlling the cooling rate of the liquid alloy in the crucible has been developed. The semi-solid slurry formed by cooling is transferred from the crucible to a casting apparatus and cast without requiring an intermediate solidified ingot. This method is referred to as “slurry on demand”.

  U.S. Patent No. 6,595,266 issued July 22, 2003 to Orii discloses such a slurry-on-demand system where molten alloy passes over a cold plate and collects in a crucible, Hold for a short time, grow to preferred grain morphology and cast.

  EP 0 745 694 (according to Adachi et al.), Issued April 12, 1996, controls the initial alloy temperature, grain refinement additive, and temperature drop rate in a crucible, 1 shows a slurry-on-demand system that obtains the desired morphology as it solidifies.

  U.S. Pat. No. 6,428,636 issued August 6, 2002 to Dooutre et al. Cools a molten alloy to a predetermined temperature within the semi-solidified range in a crucible of a specific heat capacity and temperature, and 1 shows a slurry-on-demand system that discharges some of the excess molten alloy before transferring this semi-solid to the casting mold. The step of discharging the surplus molten alloy separates the semi-solid body from the inner wall of the crucible and makes the movement of the semi-solid body to the casting apparatus more efficient. In crucibles that do not have such a discharge mechanism, there is often a problem that material sticks to the inner wall of the crucible, and it is necessary to carry out a specific cleaning process during use of the crucible. As a result, the casting cycle time (or one time required) becomes longer, and the apparatus required for obtaining and casting the slurry becomes complicated.

  The complete and reliable removal of metal from the crucible used to produce the slurry is an important requirement for increasing reliability and ensuring efficiency in a slurry on demand system. For example, it is advantageous to improve the metal removability even when the method is relatively efficient in moving the slurry, such as when discharging or reducing the adhesion force of the metal to the crucible. is there. In such a case, it is important that the liquid phase discharge means is also free of contamination and free of molten metal that solidifies later and clogs the opening.

  Accordingly, there is a need for an improved crucible structure and crucible usage method suitable for a slurry-on-demand process that increases the number of iterations during cleaning and / or repair, and allows maintenance of the cleanliness of the material during use. There is.

  In one aspect of the invention, therefore, a crucible for obtaining a semi-solid metal slurry having a liquid phase and a solid phase is provided. The crucible has a side wall having a lower edge, a closing plate that can be engaged with and separated from the lower end of the side wall, and a closing plate that contacts the lower end of the side wall. And clamping means for holding.

  In another aspect of the invention, a method is provided for preparing a semi-solid slurry having a liquid phase and a solid phase. The method includes the steps of preparing a crucible having a side wall with a lower end and a closing plate, a step of holding the closing plate in contact with the lower end of the side wall, and a step of filling the crucible with molten metal Cooling the molten metal so as to form a semi-solid slurry, closing the lower end of the side wall from the contact with the plate, and finally moving the semi-solid slurry from the side wall to the casting apparatus. Including.

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.
Referring to FIG. 1, a crucible 1 configured to receive molten metal that becomes a semi-solid metal slurry is shown. A crucible 1 is formed from a side wall having the form of an open ended tube 2 placed on a closing plate 3. Any convenient shape may be used, but a generally cylindrical shape is particularly preferred. The tube 2 is held in contact with the closing plate 3 so that the lower end 4 of the tube 2 and the surface of the closing plate 3 form a seal.

  Tube 2 is preferably slightly tapered, more preferably less than about 5 °, and most preferably about 1 °. The taper may be applied in either direction, but most preferably, the lower end 4 in contact with the closing plate 3 has a larger diameter. The closing plate 3 can be placed in sequence on a larger support plate 5 that forms part of the support portion of the crucible 1. The pressure between the tube 2 and the closing plate 3 can be maintained by a number of means known in the art, including the use of a clamping device 14. Preferably, the clamping device 14 has the form of a horseshoe-shaped clamp, is connected to the support plate 5 and further above the lower end 4 and rotates onto the flange 6 that surrounds the periphery of the tube 2 to reach the flange. 6 can be remotely actuated to clamp. The clamp can be actuated by air pressure or hydraulic pressure (or oil pressure or water pressure).

  The support plate 5 can be remotely controlled so that the indicator plate 5 swirls, thereby aggregating the crucible as it forms a semi-solid slurry and promoting cooling of the molten metal.

  The closing plate 3 may be made from a refractory material, in particular an alumina silicate refractory plate such as N-17 from Pyrotek, or may be a metal such as steel, stainless steel or titanium.

  Like the metal, the metal tube 2 may be made of a refractory material, preferably made of steel or stainless steel. In a preferred embodiment, the tube 2 material and tube thickness, and the capping plate 3 material and size are based on the predetermined heat capacity and weight required to stabilize the molten metal into the desired semi-solid slurry. decide. However, it is also possible to use an external heating or cooling system in combination without determining the tube and shroud characteristics in great detail. All metal surfaces of the closing plate 3 or tube 2 are preferably coated with a coating having a suitable metal durability. Such coatings are well known in the art and in the case of aluminum alloys include mica wash (or wash coated mica, mica wash) and boron nitride. Using any other feasible refractory-based coating and coating method, including a washcoat (or wash coat), a coating applied as a spray coating, or a coating applied by plasma spraying Good.

  With reference to FIG. 2, the closing plate 3 and the supporting plate 5 preferably have at least one hole 10 that penetrates the closing plate 3 and the supporting plate 5. The hole 10 is preferably tapered and the proximal portion of the lower end 4 of the tube 2 has a smaller diameter and extends therefrom. The hole 10 is preferably about 3 mm to about 5 mm in diameter. If the hole is tapered, the small side diameter is about 3 mm to about 5 mm. The diameter used depends in particular on the size of the alloy to be cast and the charge of the slurry to be obtained. The closing plate 3 may preferably have an upwardly directed conical profile so as to facilitate the discharge of the liquid metal from the hole 10. The plug 11 fits inside the hole 10 from below the support plate 5. The plug 11 may be installed on a pivotable cantilever arm 12 that can be operated to put the plug 11 in and out of the hole 10. The pivoting cantilever arm 12 can be plugged into or unplugged from the hole 10 by remote actuation and can be actuated pneumatically or hydraulically. The plug 11 can be made of any suitable material known in the art to be resistant to the molten metal, and is preferably made of boron nitride.

  In a preferred mode of operation, the tube 2 is first cooled to a predetermined temperature to assist in cooling the molten metal into a semi-solid slurry. The tube 2 can be cooled from room temperature to a temperature in the range of 100 to 150 ° C. The plug 11 is inserted into the hole 10 of the closing plate 3, and the tube 2 is clamped to the closing plate 3 by the clamping device 14. Usually, molten metal having a temperature higher than 700 ° C. is poured into the crucible 1, and the molten metal is stirred by the movement of the support plate 5 and cooled so as to form a semi-solid slurry. The semi-solidified slurry includes a liquid phase and a solid phase. A cooling method as shown in US Pat. No. 6,428,636 is particularly preferred for this purpose.

  After a predetermined time, the agitation may be left, but the plug 11 is removed from the hole 10 by pivoting of the pivotable cantilever arm 12 and some of the liquid phase flows out of the hole 10. As some liquid phase is drained, the proportion of solid phase in the slurry increases, typically from about 35 wt% to about 40 wt% to about 45 wt% to about 55 wt%.

  It is preferable to use a single relatively large hole 10 to discharge a part of the liquid phase, but the semi-solid structure and thixotropic behavior of the slurry inside the crucible 1 is that the solid phase is discharged. And only the liquid phase is removed. As mentioned above, it is desirable to drain some liquid phase and the semi-solid slurry in the crucible 1 leaves the tube 2 of the crucible 1 so that the slurry can be easily transferred to the casting apparatus.

  Once some liquid phase is drained, the clamping device 14 is released from the tube 2 and the tube 2 containing the semi-solid body is placed in a shot sleeve of a conventional die-casting device to form and solidify the slurry. Moving. The semi-solid slurry passes through the lower end of the tube 2 and exits from the tube 2. The tube may be moved using any means known in the art, such as using a remotely controlled robot (not shown).

  When the fastening state of the tube 2 is released and the tube is removed from the support plate 5, the hole 10 of the closing plate 3 can clean the molten metal. Such molten metal can accumulate and leave the hole 10 if left alone. Since there is no filter element required in the hole 10 in a similar device, there is little surface area on which the molten metal is deposited and the removal of small residues is completed quickly. Please refer to FIG. The hole 10 is preferably cleaned by a simple burst of compressed air from an air jet 8. Hole 10 and closing plate 3 are then ready to be fastened with tube 2 to form the next batch of semi-solid slurry. The air jet 8 may be remotely operated to remotely move to a position below the hole 10 to deliver a burst of compressed air. The operation of the air jet 8 can be performed by air pressure and hydraulic pressure.

  A rotating air jet (not shown) may be preferably used to blow away the molten metal droplets adhering to the tube after the semi-solid slurry has moved to the casting apparatus.

  Thus, the step of clamping the support plate 5 to the tube 2, the step of moving the support plate 5 vigorously, the step of releasing the tube 2 from the clamp with the support plate 5, the step of transporting the slurry to the casting mold, Each of the step of cleaning the hole 10 and the step of re-clamping the tube 2 to the support plate 5 can be operated, automated, and remotely controlled at a specified time.

  Due to its unique construction characteristics, the crucible 1 does not produce severe metal residues, especially when used in a preferred manner, and without interruptions every casting cycle for mechanical cleaning and recoating. Can be reused.

  The detailed description of the apparatus and method according to the present invention is used to describe the main embodiment of the present invention. It will be apparent to those skilled in the art that modifications to the apparatus and method of the present invention are possible, or that various other embodiments may be utilized. Accordingly, it will be appreciated that modifications can be made thereto without departing from the scope of the invention which is limited only by the appended claims.

It is a vertical sectional view of an embodiment concerning the present invention, and shows a side wall and a closing board of a crucible. FIG. 2 is a detailed view of FIG. 1, showing the plugged hole and plug. FIG. 4 is a vertical sectional view of the support plate and the closing plate, showing a preferred cleaning means for the holes.

Claims (34)

A crucible for adjusting a semi-solid metal slurry having a liquid phase and a solid phase,
(A) a sidewall having a lower end;
(B) a closing plate that can be engaged and separated from the lower end of the side wall;
(C) clamping means for holding the closing plate in contact with the lower end of the side wall;
A crucible comprising:   The crucible according to claim 1, wherein the closing plate is attached to a supporting plate that supports the closing plate and the side wall.   The crucible of claim 2, further comprising at least one independent hole formed through the closure plate and the support plate, capable of being closed, and capable of discharging at least a portion of the liquid phase from the crucible. .   The crucible according to claim 2, wherein the clamping means is attached to the support plate.   The crucible according to claim 4, wherein the clamping means includes a horseshoe-shaped clamp attached to the support plate and releasably clamping the closing plate to the side wall.   The crucible according to claim 5, further comprising a flange on which the side wall is a flange proximate to the lower end, and the clamp means is engageable so that the side wall can be clamped to the closing plate.   The crucible according to claim 6, wherein the clamping means has means for operating by air pressure or hydraulic pressure.   The crucible according to claim 7, wherein the clamping means has remote operation means capable of remotely operating the clamping means.   The crucible according to claim 1, wherein the side wall is formed by an open tube.   The crucible according to claim 9, wherein the tube is tapered so that the lower end has a larger diameter.   The crucible according to claim 10, characterized in that the tube is made of a refractory material or metal.   The crucible according to claim 11, wherein the tube is made of metal.   The crucible according to claim 12, wherein the metal is steel or stainless steel.   The crucible according to claim 13, wherein the metal is coated with a protective film.   The crucible according to claim 14, wherein the protective film is mica wash or boron nitride.   The crucible according to claim 1, wherein the closing plate is made of a refractory material or metal.   The crucible according to claim 15, wherein the refractory material is an aluminosilicate refractory plate.   The crucible according to claim 16, wherein the metal is a metal selected from the group consisting of steel, stainless steel, and titanium.   The crucible according to claim 18, wherein the metal is coated with a protective film.   The crucible according to claim 19, wherein the protective film is mica wash or boron nitride.   The crucible according to claim 1, wherein the closing plate has a conical outline facing upward.   The crucible of claim 2, wherein the at least one hole is tapered so as to have a smaller diameter proximate the lower end of the side wall.   The crucible according to claim 22, characterized in that the smaller diameter of the at least one tapered hole is between 3 mm and 5 mm.   24. The crucible of claim 23, further comprising at least one plug to close the at least one hole.   25. A crucible according to claim 24, wherein the at least one plug is made of a material that is durable against molten metal.   26. The crucible according to claim 25, wherein at least one plug is made of boron nitride.   27. A crucible according to claim 26, characterized in that the plug is placed on a pivoting cantilever arm that allows the plug to be inserted into and removed from the hole.   28. A crucible according to claim 27, wherein the pivoting cantilever arm has remote actuating means allowing remote actuation of the arm in and out of the hole.   29. A crucible according to claim 28, wherein the pivoting cantilever arm has means for actuating by air pressure or hydraulic pressure. A method for producing a semi-solid slurry having a liquid phase and a solid phase,
(A) preparing a crucible having a side wall with a lower end and a closing plate;
(B) a step of contacting and holding the closing plate in contact with the lower end of the side wall;
(C) filling the crucible with molten metal;
(D) cooling the molten metal to form a semi-solid slurry,
(E) releasing the lower end of the side wall from contact with the closing plate;
(F) moving the semi-solid slurry from the sidewall to the casting apparatus;
The manufacturing method characterized by including.   31. The method of claim 30, further comprising the step of discharging at least a portion of the liquid phase through at least one independent hole in the crucible plug after cooling the molten metal.   32. The method of claim 31, further comprising the step of cleaning the at least one independent hole with compressed air after the closing plate is released from the side wall.   31. The method of claim 30, further comprising stirring the molten metal in the crucible so as to cool the molten metal.   31. The method of claim 30, further comprising cooling the sidewalls before filling the crucible with molten metal.

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