JP2007330975A - Semi-solid casting apparatus and semi-solid casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semi-solid casting apparatus capable of suppressing an oxide, which is formed on the surface layer of a billet, from intruding into local positions of a cast product, so that a cast product of excellent quality is obtained. <P>SOLUTION: A semi-solid casting apparatus 1 is used for casting a cast product by injecting a billet B in a semi-solid state into a mold 30 from a sleeve 11 with a plunger 12. The apparatus 1 is provided with a means 20 for shattering an oxide film f formed on the surface of the billet B. The shattering means 20 is provided with contacts 22 for applying ultrasonic waves to the oxide film f. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for casting using a billet in a semi-molten state, and more particularly to a semi-melt casting apparatus suitable for crushing an oxide film formed on a billet surface heated to a semi-molten state. And its method.

  Conventionally, a casting method using a metal material having a crystal structure including a granular α phase in which dendrites are divided and a eutectic structure filling them is widely known. Specifically, in this casting method, a billet that is a metal material is heated to a state where a solid phase α phase and a liquid phase (molten eutectic structure) coexist (solid-liquid coexistence state), and the billet is used as a mold. The product is cast by press-fitting into the cavity. According to such a method, since the α phase in the metal material has a nearly spherical shape, α homology is not entangled at the time of casting, so that excellent formability can be obtained. Furthermore, since the temperature difference between the molding temperature of the material and the solidification temperature is small, a high-quality cast product having a small dimensional shrinkage and a good dimensional accuracy can be obtained.

  In addition to this, after dissolving the metal material, it is cooled with electromagnetic stirring so that the crystallized α phase is divided, and the metal is in a semi-solid state in which the solid phase (α phase) and the liquid phase coexist. A method of casting using a material may be taken. This method is sometimes called a semi-solid casting method, and is widely used because it has the same advantages as the semi-molten casting method.

  By the way, the billet is generally manufactured by centrifugal stirring, and the oxide in the billet has a large specific gravity, so that it easily moves in the outer circumferential direction. Furthermore, the billet manufactured by centrifugal stirring is heated so that the solid phase ratio becomes 30% to 50% before casting, and the billet surface is more likely to be oxidized by touching the atmosphere than the inside. Thus, an oxide film is formed on the surface of the billet before casting by centrifugal stirring and atmospheric contact. This oxide film may locally enter the cast product after molding as an oxide, and in this case, the cast product may not partially obtain a desired strength.

  In view of such a problem, for example, as shown in FIG. 6, an injection sleeve 71, a plunger 72 installed in the injection sleeve 71 and capable of moving back and forth in the axial direction of the injection sleeve 71, the injection sleeve 71 and the mold 60. A molding apparatus 70 is proposed that includes at least a slide die 74 in which a protrusion 74A is formed so as to have an inner diameter smaller than the inner diameter of the injection sleeve 71 (see Patent Document 1). In such a device 70, the protrusion 74A is formed to have a diameter smaller than the sleeve diameter, and when the billet B is injected, the protrusion 74A includes a surface layer including an oxide film formed on the surface of the billet B. The part is cut away so that the oxide film is not put into the casting.

Japanese Patent Laid-Open No. 10-175054

  However, when a casting apparatus as described in Patent Document 1 is used, the surface layer portion of the billet B can be scraped off by the protruding portion 74A using the pressure applied by the plunger, but the scraped oxide film is removed. As shown in FIG. 6, the film-containing material C having a high solid phase ratio is deposited on the rear side in the plunger injection direction of the protrusion 74 </ b> A and may be wound into the billet B again (the white arrow in FIG. 6). . As a result, the film-containing material C wound in the billet B flows as a lump into the cavity 61 of the mold 60 together with the semi-molten alloy material, and may enter the cast product locally. As a result, the cast product cannot obtain a desired strength as described above, resulting in poor quality.

  The present invention has been made in view of such problems, and the object of the present invention is in semi-molten casting in which a cast product is cast into a mold cavity using a billet in a semi-molten or semi-solid state. The present invention provides a semi-molten casting apparatus and a semi-molten casting method in which oxides formed on the surface of a billet during billet injection are prevented from entering the cast product locally and a good cast product can be obtained. There is.

  Therefore, the present inventor has focused on the fact that such an oxide film is fine and easily crushed because the oxide film formed on the billet is thin and brittle compared to a semi-molten billet. Based on this point, the inventor conducted a lot of experiments and research, so that if the oxide film is finely crushed in advance before injection, even if the oxide film gets into the casting, it is dispersed and oxidized. A new finding was obtained that the film penetrates into the cast product and hardly reduces the strength of the cast product.

  The present invention is based on such new knowledge, and the semi-molten casting apparatus according to the present invention casts a cast product by injecting a semi-molten billet from a sleeve into a mold using a plunger. A semi-molten casting apparatus for the above-mentioned, the apparatus comprising means for crushing an oxide film formed on the surface of the billet, the crushing means comprising at least a contact for applying ultrasonic waves to the oxide film It is characterized by being.

  According to such a semi-molten casting apparatus, the billet oxide film immediately before injection molding can be crushed by bringing the contact into contact with the billet oxide film. As a result, after the oxide film is crushed and before a new oxide film is formed on the billet surface by heat dissipation, it is possible to perform casting quickly using a billet in a good formability. Obtainable. In particular, by applying ultrasonic waves, the oxide film can be finely crushed and the oxide film can be uniformly dispersed in the cast product, thus suppressing the strength reduction of the cast product due to the presence of the oxide film. Can do.

  It is preferable that the contact is disposed at a position where the contact can move relative to the billet. With the arrangement of such contacts, ultrasonic waves can be applied over the entire length of the billet. In particular, the contacts are preferably arranged along the injection direction of the plunger, and a plurality of such contacts may be arranged along the injection direction. In this case, since the oxide film of the full length of the billet can be crushed using the existing plunger, the oxide film can be crushed efficiently and inexpensively.

  The semi-molten casting apparatus according to the present invention includes at least two contacts, and each contact is configured to be able to apply ultrasonic waves having different amplitudes or frequencies to the oxide film. Accordingly, it is more preferable that the billet is rotated about an axis along the injection direction of the plunger as a rotation axis. In order to rotate the billet more efficiently, the two contacts are preferably arranged so as to face each other across the billet. By rotating the billet in this way, even when the contact area between the contact and the oxide film is small, it is possible to apply ultrasonic waves to the entire peripheral surface of the billet, and effectively apply the oxide film. Can be crushed. If the billet is rotatable, ultrasonic waves may be applied to only one of the two contacts.

  The semi-molten casting apparatus according to the present invention further includes a plate-like body in which at least two of the contacts contact the billet, and the two plate-like bodies are billets in the sleeve. Is arranged in an inverted C shape in a cross section perpendicular to the injection direction so as to coincide with the axis of the sleeve.

  By providing such a plate-like body, ultrasonic waves can be efficiently applied to the billet. In order to efficiently apply ultrasonic waves, the thickness of the plate-like body is preferably 2 mm to 3 mm. Furthermore, the plate-like body is preferably made of stainless steel such as SUS304, SUS316 (JIS standard) in consideration of corrosion resistance and durability. The two contactors are arranged so that the billet in the sleeve coincides with the axial core of the sleeve. Therefore, the billet and the sleeve are not aligned after the oxide film is crushed in the sleeve. Can be injected into the mold. As a result, a good casting can be promptly cast from a billet having a good formability without substantially increasing the solid phase ratio of the billet. Furthermore, since the two plate-like bodies are arranged in an inverted C shape in a vertical section with respect to the injection direction, the billet and the sleeve can be easily aligned. In particular, when an opening for introducing a billet is provided on the sleeve upper peripheral surface at a position facing the inverted C-shaped contact, the billet can be easily put into the sleeve, and work efficiency can be improved.

  As the present invention, a more preferable casting method using such a semi-molten casting apparatus is also disclosed. A semi-molten casting method according to the present invention is a semi-molten casting method in which a billet in a semi-molten state is injected from a sleeve into a mold using a plunger to cast a cast product. The method includes at least a step for crushing an oxide film formed on the surface. The crushing step of the oxide film is performed by bringing a contact into contact with the oxide film in the sleeve and applying ultrasonic waves from the contact to the oxide film. It is characterized by things.

  In this way, by performing semi-molten casting, it becomes possible to disperse and enter the oxide film formed on the billet surface into the cast product, and it is possible to obtain a good cast product with no strength reduction. .

  According to the casting method of the present invention, the material of the billet is not particularly limited as long as it satisfies the conditions of performing casting in a semi-molten state and forming an oxide film, Considering ease of use, it is effective for billets of aluminum alloys and magnesium alloys.

  In such a crushing step, it is preferable to apply the ultrasonic wave while relatively moving the billet and the contactor. When such relative movement is performed in accordance with the movement of the plunger in the injection direction, the step of crushing the oxide film and the step of injecting the billet into the mold can be performed continuously. . As a result, it is possible to suppress a rise in the solid phase ratio due to heat radiation of the billet, and to cast a cast product from the billet having a good formability.

  Furthermore, at least two of the contacts are used, and ultrasonic waves having different amplitudes or frequencies or both are applied to the oxide film from each of the contacts, whereby an axis along the moving direction of the plunger. It is preferable that the crushing is performed while rotating the billet about the rotation axis. In particular, when a columnar billet is used, the billet can be easily rotated, and the oxide film on the entire peripheral surface of the billet can be suitably crushed.

  When the semi-molten apparatus according to the present invention is used, or when the semi-molten casting method is performed, the oxide film formed on the billet surface can be dispersed and taken into the cast product. Strength reduction can be reduced. As a result, it is possible to produce a high-quality cast product.

Hereinafter, a semi-molten casting apparatus will be described based on an embodiment with reference to the drawings.
1 shows an overall configuration diagram of a semi-molten casting apparatus 1 according to the present embodiment, FIG. 2 shows a side view of FIG. 1, and FIG. 3 shows a cross-sectional view taken along line AA of FIG. Yes. FIG. 4 is a diagram for explaining the semi-molten casting method according to this embodiment.

  As shown in FIG. 1, a semi-molten casting apparatus 1 according to this embodiment includes an injection apparatus 10 for injecting a billet B, and a crushing apparatus (crushing means for crushing an oxide film of the billet B in the injection apparatus 10. ) 20 at least.

  The injection device 10 includes a long cylindrical sleeve 11 into which the billet B can be inserted, a plunger 12 slidably fitted from one end of the sleeve 11 to the inner surface, and an injection direction ( And a pressurizing device 13 for pressurizing the billet B in the direction of the arrow in FIG. The other end of the sleeve 11 is connected to the mold 30, and the injection device 10 can inject the billet B pressurized through the plunger 12 by the pressure device 13 into the cavity 31 in the mold 30. It has become. Furthermore, an opening 11 a into which the billet B can be inserted is formed on the upper peripheral surface near the pressure device 13 side from the center of the sleeve 11.

  The crushing device 20 includes at least two ultrasonic generators 21 and 21 that generate ultrasonic waves, and contacts 22 and 22 that contact the billet B. Each of the ultrasonic generators 21 is configured to generate ultrasonic waves having different amplitudes or frequencies, or both, and the generated ultrasonic waves are connected to the contactor 22 so as to be transmitted.

  Each contact 22 is fixed via a channel or the like (not shown), and the contact 22 can be attached to and detached from the columnar vibrator 22a connected to the ultrasonic generator 21 and the vibrator 22a. And a connected plate-like body 22b. As shown in FIG. 2, the plate-like body 22 b is arranged at a position where it can move relative to the billet B when the plunger 12 is moved in the injection direction. Further, as shown in FIG. 3, one end of the plate-like bodies 22 b and 22 b is arranged so that the billet B in the sleeve 11 coincides with the axis L of the cylindrical sleeve 11 through the opening 11 a of the sleeve 11. In the vertical cross section with respect to the injection direction, they are arranged in an inverted C shape. In the present embodiment, two contacts are provided so as to face each other in the sleeve 11, but contacts may be further provided along the injection direction of the plunger 12.

  A semi-molten casting method performed using the semi-molten casting apparatus 1 configured as described above will be described below with reference to FIG. First, billet B is prepared and heated. Specifically, the billet B to be prepared is a material having a crystal structure including a granular α phase in which dendrites are divided and a eutectic filling them. And billet B is heated so that it may be in the semi-molten state in which a solid phase and a liquid phase coexist. In addition, after melt | dissolving a metal material, you may cool with electromagnetic stirring so that the (alpha) phase crystallized may be divided, and you may heat to the semi-solidified state in which a solid phase and a liquid phase coexist.

  The billet B in a semi-molten or semi-solid state heated in this manner is put into the sleeve 11 through the opening 11a (see FIG. 4A). At this time, since the plate-like bodies 22b and 22b of the two contactors 22 and 22 are arranged so as to have an inverted C shape as described above, the billet B and the sleeve 11 have a shaft core. Match.

  Next, the oxide film crushing step as shown in FIG. Specifically, the plate-like bodies 22b and 22b of the contacts 22 and 22 are brought into contact with the oxide film f of the billet B in the sleeve 11, and the ultrasonic waves of the ultrasonic generator 21 are used to remove the plate-like bodies 22b and 22b. An ultrasonic wave is applied to the oxide film f. In addition, when applying ultrasonic waves, each ultrasonic generator is operated so that ultrasonic waves having different amplitudes or frequencies or both can be applied to the oxide film from the respective contacts 22, 22. By applying ultrasonic waves having such different characteristics to the billet B, the oxide film is crushed while the billet B is rotated about the axis (specifically, the axis L) along the moving direction of the plunger 12 as the rotation axis. It can be carried out.

  Further, while rotating the billet B, the plunger 12 is moved along the injection direction using the pressurizing device 13. As a result, the oxide film in the circumferential direction and the axial direction of the billet B can be efficiently crushed even when the contact area between the plate-like body 22b of the contactor 22 and the oxide film f is small. Then, as shown in FIG. 4C, the billet B with the oxide film crushed is injected from the sleeve 11 into the cavity 31 in the mold 30 using the plunger 12 to cast a cast product. In this manner, the oxide film f on the entire peripheral surface of the billet immediately before injection can be crushed and dispersed and taken into the cast product, and a high-quality cast product with no strength reduction can be cast.

  In addition, since the long cylindrical sleeve 11 is used, the surface of the billet B can be crushed by one apparatus until the plunger 12 passes through the opening 11a as the first step, and continuously. As a second step, the cast product can be cast by moving the plunger in the injection direction after passing through the opening 11a, and a non-defective cast product can be obtained with a simple device configuration. In particular, when the casting shown in the present embodiment is performed using the existing casting equipment, only the sleeve 11 needs to be modified, so that the casting of the present embodiment can be performed at low cost.

  Further, by providing the sleeve 11 with the opening 11a and arranging the contacts 22 and 22 through the opening 11a, the behavior of the rotation of the billet B and the movement in the injection direction can be visually confirmed. The oxide film f can be reliably crushed.

Examples according to this embodiment will be described below.
Example 1
Casting was performed using a semi-molten casting apparatus as shown in FIG. First, a cylindrical aluminum alloy billet of 150 mm in diameter and 600 mm in length (ADC12: JIS standard) was prepared. Next, this billet was heated to a semi-molten state, the heated billet was placed in the sleeve of the injection device, and the billet was brought into contact with the two contacts of the crushing device.

  In such a contact state, the ultrasonic generator is operated so that the frequency of one ultrasonic wave is 20 kHz and the frequency of the other ultrasonic wave is 40 kHz, and ultrasonic waves are applied from the contact to the oxide film on the billet surface. Applied. Thereby, the billet was rotated about the axis along the injection direction of the plunger as the rotation axis. Note that stainless steel (SUS304: JIS standard) having a plate thickness of 3 mm and a width of 120 mm was used for the plate-like body of the contact. On the other hand, the plunger is moved at a speed of 10 mm / sec, and the rotating billet is further moved in the injection direction, the billet and the contact are moved relative to each other, and the oxide film on the entire periphery of the billet is crushed. .

  Then, the speed of the plunger was set to 500 mm / sec, and the billet in which the oxide film was crushed was injected from the sleeve into the mold using the plunger to cast a cast product of the single cylinder cylinder block. Then, a cast product was taken out from the mold, cut out from the cast product into a test piece (corresponding to JIS No. 14A) having a parallel cross section of 5 mm in diameter, and a tensile test was performed on the test piece. The result is shown in FIG.

(Comparative Example 1)
A casting similar to that in Example 1 was cast. The difference from Example 1 is that the cast product was cast without crushing the oxide film formed on the surface of the billet. And the test piece was cut out from the casting similarly to Example 1, and the tension test was done with respect to this test piece. The result is shown in FIG.

(result)
As shown in FIG. 5, the tensile strength of the test piece of Example 1 was about 280 MPa, whereas that of Comparative Example 1 was about 200 MPa, and the strength of the cast product of Example 1 was comparative. Lower than that of Example 1.

(Discussion)
When the oxide film is crushed by ultrasonic waves before casting as in Example 1, the crushed oxide film is dispersed in the cast product, so that the strength of the cast product is higher than that of Comparative Example 1. It is thought that became higher.

1 is an overall configuration diagram of an embodiment of a semi-molten casting apparatus according to the present invention. The side view of the semi-molten casting apparatus shown in FIG. AA arrow sectional drawing of FIG. It is a figure for demonstrating the semi-molten casting method which concerns on this embodiment, (a) is the figure which has arrange | positioned a billet in a sleeve, (b) crushes the oxide film formed in the billet surface It is the figure which showed the process, (c) is the figure just before inject-molding a casting from a billet. The figure which showed the result of the tension test of the castings of Example 1 and Comparative Example 1. The figure for demonstrating the conventional semi-molten casting apparatus.

Explanation of symbols

  1: semi-molten casting apparatus, 10: injection apparatus, 11: sleeve, 12: plunger, 13: pressurizing apparatus, 20: crushing apparatus, 21: ultrasonic generator, 22: contactor, 22a: vibrator, 22b: Plate

Claims (7)

A semi-molten casting apparatus for casting a semi-molten billet from a sleeve into a mold using a plunger to cast a cast product,
The apparatus comprises means for crushing an oxide film formed on the surface of the billet,
The crushing means includes a contact for applying an ultrasonic wave to the oxide film.   The semi-molten casting apparatus according to claim 1, wherein the contact is disposed at a position relatively movable with the billet in the sleeve.   There are at least two contacts, and each contact is configured to be able to apply ultrasonic waves having different amplitude or frequency to the oxide film, and thereby in the injection direction of the plunger. The semi-molten casting apparatus according to claim 1 or 2, wherein the billet is rotated about an axis along the rotation axis.   At least two of the contacts are each provided with a plate-like body that contacts the billet, and the two plate-like bodies are arranged so that the billet in the sleeve coincides with the axis of the sleeve. 4. The semi-molten casting apparatus according to claim 3, wherein the semi-molten casting apparatus is arranged in an inverted C shape in a vertical section with respect to the injection direction. 5. A semi-molten casting method in which a billet in a semi-molten state is injected from a sleeve into a mold using a plunger to cast a cast product,
The semi-molten casting method includes a step for crushing an oxide film formed on the surface of a billet,
The semi-molten casting method, wherein the crushing step of the oxide film is performed by bringing a contact into contact with the oxide film in the sleeve and applying ultrasonic waves from the contact to the oxide film.   The semi-molten casting method according to claim 5, wherein the ultrasonic wave is applied while the billet and the contact are relatively moved.   Using at least two of the contacts, ultrasonic waves having different amplitudes or frequencies or both are applied from the contacts to the oxide film, thereby rotating the axis along the moving direction of the plunger. The semi-molten casting method according to claim 5 or 6, wherein the crushing is performed while rotating the billet as an axis.

Images