JP3670164B2 - Method for casting metal matrix composite - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for casting a metal matrix composite material by impregnating a preform made of reinforcing fibers with a molten metal alloy.
[0002]
[Prior art]
A metal matrix composite material in which a light alloy such as an aluminum alloy is infiltrated into a reinforcing fiber such as an alumina fiber is known. The metal matrix composite material is disposed, for example, on the inner surface of a hole (bore) in which a cylinder slides in a cylinder block of an internal combustion engine.
[0003]
The cylinder block is cast from an aluminum alloy using the mold casting apparatus 1 shown in FIG. In the mold casting apparatus 1, the preheated cylindrical preform 5 is placed on the mounting table 6 of the fixed mold 2, the movable mold 4 is lowered, and the bore pin 7 is placed on the inner peripheral side of the cylindrical preform 5. , And the mold is closed and clamped to form the cavity 3 having a shape along the outer shape of the cylinder block. Then, the molten aluminum alloy is filled into the cavity 3 from a not-shown gate system and the cylinder block is cast, so that the cylindrical preform 5 is simultaneously infiltrated with the molten aluminum alloy. As a result, the inner surface of the bore is made of a metal matrix composite material in which an aluminum alloy penetrates the cylindrical preform 5, and the cylinder block integrated with the cylindrical preform 5 can be obtained.
[0004]
Here, if the operation of placing the preheated cylindrical preform 5 on the mounting table 6 is performed manually, the orientation of the cylindrical preform 5 is not necessarily determined when the cylindrical preform 5 is mounted on the mounting table 6. It will not be the same. Moreover, the time which each cylindrical preform 5 is exposed to external air can shift | deviate by the order which mounts each cylindrical preform 5 on the mounting base 6. FIG. As a result, the temperature conditions and the like of each cylindrical preform 5 cannot be made uniform. Therefore, the above work is conventionally performed by the robot apparatus 11 shown in FIG.
[0005]
According to the robot apparatus 11, first, a plurality of cylindrical preforms 5 placed in an aligned state in advance on the alignment table 12 are supported by the support unit 15 provided in the operation arm unit 14, and are subjected to high-frequency heating. It moves to the container 13, and it heats by hold | maintaining in the high frequency heater 13 for predetermined time. Next, the robot apparatus 11 moves the plurality of cylindrical preforms 5 from the high-frequency heater 13 into the fixed mold 2 while being supported by the support portion 15. Then, the support by the support portion 15 is released at a predetermined position in the fixed mold 2 and the support portion 15 is removed from the cylindrical preform 5, whereby the heated cylindrical preform 5 is placed on the mounting table 6. Place.
[0006]
According to the robot apparatus 11, the plurality of cylindrical preforms 5 are held in the same arrangement throughout the alignment stage 12 while being aligned on the alignment table 12. It is mounted on the mounting table 6. Accordingly, it is possible to prevent deviations in the arrangement of the cylindrical preforms 5 and the time of exposure to the outside air, and to make the temperature conditions uniform.
[0007]
However, when the cylindrical preform 5 is placed on the mounting table 6 in the fixed mold 2 by the robot apparatus 11 and the casting is performed, the inner surface of the bore of the cylinder block obtained at the time of mold release after casting. Has the disadvantage of being damaged.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for casting a metal matrix composite that can eliminate such inconvenience and prevent damage to a cast product at the time of mold release.
[0009]
[Means for Solving the Problems]
As a result of repeated studies on the reason why the inner surface of the bore of the cylinder block obtained at the time of mold release after casting is damaged, the present inventors have discovered that the damage is a cylindrical shape arranged linearly as described above. It has been found that this occurs at the portion sandwiched between the preforms 5 and 5. The present inventors have further studied the phenomenon, and the molten metal permeates the preform 5 excessively at the portion sandwiched between the cylindrical preforms 5 and 5 arranged linearly. It has been found that welding is performed between the preform 5 and the bore pin 7.
[0010]
After the preform 5 is heated as described above, the preform 5 is cooled to some extent by being exposed to the outside air before being placed in the fixed mold 2. In the sandwiched portion, it is difficult to be exposed to the outside air, but it is difficult to be cooled because of mutual heat radiation. For this reason, the part which each preform 5 faced at the time of the heating becomes higher temperature than the part only exposed to other outside air. And since the said molten metal becomes easy to flow into a high temperature part, it is thought that the excessive penetration of the said molten metal generate | occur | produces in this part.
[0011]
Therefore, in order to achieve the above object, the casting method of the metal matrix composite material of the present invention comprises a plurality of cylindrical preforms composed of reinforcing fibers arranged in a straight line at a predetermined interval. A process of holding and heating the preform in an aligned state by a holding means that detachably holds the reform, and the heated preform is disposed at a predetermined position in the mold of the casting apparatus to release the holding by the holding means. In the casting method of casting the metal matrix composite material by infiltrating the melt into the preform by filling the mold with the molten metal after clamping the casting apparatus The preform is characterized in that the mold is clamped in a state where at least surfaces of the preforms facing each other at the time of heating are separated from each other.
[0012]
According to the casting method of the present invention, each preform heated as described above is rotated, and the casting apparatus is clamped in a state where at least the surfaces facing at the time of heating are separated from each other. The portion that is difficult to be cooled is eliminated, and the temperature of each part of the preform is made uniform. As a result, the welding due to excessive penetration of the molten metal can be eliminated, and damage to the cast product at the time of mold release can be prevented.
[0013]
Each of the preforms only needs to be in a state where the surfaces facing each other at the time of heating are separated from each other when the casting apparatus is clamped, and the rotation of each preform is held by the holding means. It may be performed during conveyance, or may be performed after being disposed in the mold. However, the rotation of each preform is preferably performed while being conveyed by being held by the holding means because the cycle time can be shortened.
[0014]
The casting method of the present invention can be applied, for example, when the metal matrix composite material constitutes a part of a cylinder block of an internal combustion engine.
[0015]
In the casting method of the present invention, each preform is rotated in a range of 30 to 150 °. If the rotation angle of each preform is less than 30 °, the faces facing at the time of heating are not sufficient to be separated from each other, and if it exceeds 150 °, adjacent preforms on the other side aligned in a straight line. The reforming and the surfaces facing at the time of heating are opposed to each other, so that it is difficult to be cooled again.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory sectional view showing a configuration example of a mold casting apparatus used in the present embodiment. FIG. 2 is a plan view showing the arrangement of a cylinder block manufacturing apparatus used in the present embodiment. 3 is an explanatory view showing a rotating method of the cylindrical preform. FIG. 4 is a graph showing the change over time in the temperature of the portion of the cylindrical preform facing the adjacent cylindrical preform. FIG. 5 is an explanatory sectional view showing another configuration example of the mold casting apparatus used in this embodiment.
[0017]
In the present embodiment, the cylinder block of the internal combustion engine is cast using the mold casting apparatus 1 shown in FIG. The mold casting apparatus 1 includes a fixed mold 2 and a movable mold 4 that forms a cavity 3 having a shape along the outer shape of the cylinder block between the fixed mold 2 and the fixed mold 2. In the fixed mold 2, a plurality of mounting tables 6 on which a pre-formed cylindrical preform 5 made of reinforcing fibers such as alumina fibers is mounted are arranged in a straight line at a predetermined interval. The movable mold 4 is provided so as to be movable up and down above the fixed mold 2, and a plurality of cylindrical bore pins 7 inserted on the inner peripheral side of the cylindrical preform 5 are mounted on the surface facing the fixed mold 2. It is provided concentrically with the table 6.
[0018]
In the mold casting apparatus 1, the preheated cylindrical preform 5 is mounted on the mounting table 6 while the movable mold 4 is moved above the fixed mold 2. Here, the operation of placing the preheated cylindrical preform 5 on the placing table 6 is performed by the robot apparatus 11 shown in FIG.
[0019]
FIG. 2 is a plan view showing a main part of a cylinder block manufacturing apparatus including the mold casting apparatus 1 shown in FIG. 1, and the manufacturing apparatus includes a mold casting apparatus 1 and a plurality of cylindrical preforms 5. The apparatus includes an alignment table 12 that is placed in advance and a high-frequency heater 13 that preheats the cylindrical preform 5, and the robot apparatus 11 is disposed between the mold casting apparatus 1 and the alignment table 12. Yes.
[0020]
On the aligning table 12, the same number of cylindrical preforms 5 as the number of cylinder blocks of the cylinder block are mounted in an aligned state in order to be mounted on the mounting table 6 in the fixed mold 2. Therefore, the robot apparatus 11 first moves the operating arm unit 14 onto the alignment table 12 and inserts the support unit 15 provided in the operating arm unit 14 into the inner peripheral side of the cylindrical preform 5 to make pressure contact. The cylindrical preform 5 is supported by the above.
[0021]
Next, the robot apparatus 11 moves the operating arm portion 14 so that the cylindrical preform 5 supported by the support portion 15 is positioned in the high-frequency heater 13, and the cylindrical preform 5 is moved to the high-frequency heater 13. It is heated for a predetermined time. Next, the robot apparatus 11 moves the operating arm section 14 so that the cylindrical preform 5 supported by the support section 15 is positioned in the mold casting apparatus 1.
[0022]
The cylindrical preform 5 is heated in the high-frequency heater 13 and then cooled to some extent by being exposed to the outside air while being moved into the mold casting apparatus 1 by the robot apparatus 11. However, since the cylindrical preform 5 is heated in the aligned state and moved into the mold casting apparatus 1 as described above, the cylindrical preform 5 adjacent to the cylindrical preform 5 as shown in FIG. The portion C facing the preform 5 is difficult to be cooled due to mutual heat dissipation.
[0023]
Therefore, the robot device 11 then rotates each cylindrical preform 5 by the support portion 15 so that the portions C facing the adjacent cylindrical preform 5 at the time of heating are separated from each other. The portion C facing the adjacent cylindrical preform 5 at the time of heating sandwiches a line D connecting the axes of the aligned cylindrical preforms 5, 5, with the axis of the cylindrical preform 5 as the center. This corresponds to an arc having a central angle of 60 °. Accordingly, in order to separate the portions C of the respective cylindrical preforms 5 from each other, it is necessary to rotate the cylindrical preform 5 by 30 ° or more by the support portion 15. However, when the rotation angle of the cylindrical preform 5 exceeds 150 °, the other side surface of the cylindrical preform 5 faces the portion C of the adjacent cylindrical preform 5.
[0024]
In this embodiment, as shown in FIG. 3B, by rotating each cylindrical preform 5 by 90 °, the portions C facing the adjacent cylindrical preform 5 at the time of heating are separated from each other. To do. As a result, there is no portion that is difficult to be cooled in each cylindrical preform 5, and the entire temperature of the cylindrical preform 5 is made uniform.
[0025]
Next, the robot apparatus 11 releases the support of the cylindrical preform 5 by the support portion 15 at a predetermined position, and removes the support portion 15 from the cylindrical preform 5, as shown in FIG. The preform 5 is placed on the placing table 6.
[0026]
The rotation of each cylindrical preform 5 may be performed prior to the operation of mounting on the mounting table 6 by the robot apparatus 11 as described above, or may be performed after mounting on the mounting table 6. . However, the cycle time can be shortened by performing the operation prior to the operation of mounting on the mounting table 6, which is advantageous.
[0027]
In the mold casting apparatus 1, when the cylindrical preform 5 is placed on the mounting table 6, the movable mold 4 is lowered and the bore pin 7 is inserted into the inner peripheral side of the cylindrical preform 5. The mold is closed and the mold is clamped to form the cavity 3 having the shape. Then, the cylinder block is cast by filling the cavity 3 with molten aluminum alloy from a not-shown gate system. According to the mold casting apparatus 1, the molten aluminum alloy is infiltrated into the cylindrical preform 5 simultaneously with the casting of the cylinder block.
[0028]
Therefore, after casting, the inner surface of the bore is constituted by a metal matrix composite material in which an aluminum alloy has permeated into the cylindrical preform 5, and the cylindrical preform 5 is combined by the aluminum alloy and integrated. A cylinder block can be obtained.
[0029]
In the mold casting apparatus 1 of the present embodiment, the aligned cylindrical preforms 5 are rotated as described above before being placed in the fixed mold 2, so that the cylindrical preform 5, the bore pin 7, The aluminum alloy is not welded between. Accordingly, it is possible to prevent the inner surface of the bore from being damaged during the mold release.
[0030]
Next, after taking out the cylindrical preform 5 from the high-frequency heater 13 and before placing it in the fixed mold 2, the cylinder is rotated (this embodiment) and not rotated (conventional example). FIG. 4 shows the change over time in the temperature of the portion of the cylindrical preform 5 facing the adjacent cylindrical preform 5.
[0031]
From FIG. 4, as shown in the present embodiment, the cylindrical preform 5 is rotated before being placed in the fixed mold 2, so that the cylindrical preform 5 faces the adjacent cylindrical preform 5. It is clear that it becomes easier to cool.
[0032]
In the mold casting apparatus 1, assuming that the time when the cylindrical preform 5 is taken out from the high-frequency heater 13 is zero, the molten aluminum alloy is filled in the cavity 3 60 seconds later. Therefore, in particular, when the temperature of the part 60 seconds after taking out from the high-frequency heater 13 is compared, it is 179 ° C. in the conventional example, but 147 ° C. in this embodiment, and is adjacent to the cylindrical preform 5. It is apparent that the part facing the cylindrical preform 5 is easily cooled.
[0033]
In the present embodiment, as described above, the mold casting apparatus 1 having the configuration in which the movable mold 4 is provided to be movable up and down above the fixed mold 2 is used, but the mold casting apparatus 21 shown in FIG. 5 is used. It may be. A mold casting apparatus 21 shown in FIG. 5 includes a fixed mold 2 provided on a fixed base 22 and a movable mold 4 provided on a slide base 24 that slides along a rod 23. A cavity 3 having a shape along the outer shape of the cylinder block is formed between the movable die 4 and the movable die 4.
[0034]
In the mold casting apparatus 21, projections 25 corresponding to the mounting table 6 of the mold casting apparatus 1 are arranged in a straight line on the surface of the fixed mold 2 facing the movable mold 4 at a predetermined interval. ing. A bore pin 7 is provided concentrically with the protrusion 25 on the surface of the movable die 4 facing the fixed die 2.
[0035]
In the mold casting apparatus 21, the preheated cylindrical preform 5 is inserted into the bore pin 7 of the movable mold 4 while the movable mold 4 is moved to the side of the fixed mold 2 (left side in FIG. 5). Arrange. Here, the operation of disposing the preheated cylindrical preform 5 on the bore pin 7 is performed with the robot device 11 shown in FIG. In the robot apparatus 11, the cylindrical preform 5 placed on the alignment table 12 is supported, and the distal end portion of the operating arm portion 14 is directed downward until the heating in the high-frequency heater 13 is completed. The cylindrical preform 5 is supported in a suspended state. When the heating is completed, the tip of the operating arm 14 is turned upward to support the cylindrical preform 5 in a horizontal state and disposed on the bore pin 7.
[0036]
The operation of separating the portions C of the cylindrical preforms 5 from each other can be performed in exactly the same way as in the mold casting apparatus 1.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a configuration example of a mold casting apparatus used in a casting method of the present invention.
FIG. 2 is a plan view showing the arrangement of a cylinder block manufacturing apparatus used in the casting method of the present invention.
FIG. 3 is an explanatory view showing a method of rotating a cylindrical preform in the casting method of the present invention.
FIG. 4 is a graph showing a change over time in the temperature of a portion of a cylindrical preform facing an adjacent cylindrical preform.
FIG. 5 is an explanatory cross-sectional view showing another configuration example of a mold casting apparatus used in the casting method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,21 ... Casting apparatus, 2 ... Fixed type | mold, 3 ... Hollow part, 4 ... Movable type, 5 ... Cylindrical preform, 7 ... Cylindrical nesting, 11 ... Holding means.

Claims (3)

A step of heating a plurality of cylindrical preforms made of reinforcing fibers arranged in a straight line at a predetermined interval while being held in an aligned state by a holding means for detachably holding the preform;
Disposing the heated preform by disposing the holding means by disposing the preform at a predetermined position in the mold of the casting apparatus;
In the casting method of casting the metal matrix composite material by filling the molten metal into the mold and clamping the molten metal into the preform after clamping the casting apparatus.
The method for casting a metal matrix composite material, wherein the preform that has been heated is clamped in a state where at least surfaces of the preforms facing each other at the time of heating are separated from each other. 2. The method for casting a metal matrix composite material according to claim 1, wherein the metal matrix composite material constitutes a part of a cylinder block of an internal combustion engine. 3. The method for casting a metal matrix composite material according to claim 1, wherein each preform is rotated within a range of 30 to 150 [deg.].

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