JP4183353B2 - Cylinder block manufacturing method and casting mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for manufacturing a cylinder block of a vehicle engine, for example.
[0002]
[Prior art]
Conventionally, in manufacturing a cylinder block of an aluminum alloy vehicle engine, a die casting method (HPDC) in which a molten aluminum alloy is filled into a mold at a high pressure as disclosed in, for example, Japanese Patent Laid-Open Nos. 7-269410 and 9-42049. ) Is generally cast.
[0003]
On the other hand, in recent years, as a technique for casting aluminum, a magnesium alloy, or the like, a casting method using a semi-solid metal in a solid-liquid coexisting state is known, for example, as disclosed in JP-A-8-57587 and JP-A-11-197814. It is possible to obtain a uniform fine structure and skin beautification, to reduce macro segregation and shrinkage nests, and because the coagulation shrinkage is small and there is little shrinkage, a near net shape is possible. It is in the limelight because it has the advantage of reducing the heat burden.
[0004]
[Problems to be solved by the invention]
By the way, for example, when a cylinder block made of an aluminum alloy is formed by a conventional general die casting method (HPDC), the casting speed (gate speed) of the molten aluminum alloy is high. As shown in the cross-sectional views of the cylinder block S in FIGS. 7 and 8, for example, as shown in the cross-sectional views of the cylinder block S, particularly, as shown in the cross-sectional views of the cylinder block S in FIGS. There is a problem that the water jacket j and the peripheral cylinder head cover coupling hole k and the like are in communication with each other through the casting hole e inside the thick wall, and the airtightness of the water jacket j is impaired and pressure leakage occurs.
[0005]
On the other hand, casting with a semi-solid metal in the coexisting state of solid and liquid reduces the amount of gas entrainment and suppresses solidification shrinkage. Therefore, the casting hole is significantly larger than the conventional die casting method (HPDC). However, in the case of a cast product with a complicated shape, it is not possible to prevent problems due to the occurrence of a cast hole such as a thick part.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent a malfunction due to the formation of a cast hole inside a cast product when casting a cylinder block, and to improve the airtightness of the water jacket.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a manufacturing method for manufacturing a cylinder block in which a water jacket is opened on a deck surface with a casting mold, a core pin for forming the water jacket, and a position of the core pin. Using a casting mold provided with opposed casting pins, pressurizing and filling a semi-solid aluminum alloy into a cavity of the casting mold, and in the solidification process, a core pin and a casting pin for forming the water jacket Was moved forward by a predetermined stroke, and the inside was partially pressurized to cast.
The casting mold according to the present invention includes a core pin for forming a water jacket, and a core pin that faces the position of the core pin and has a thick portion between the core pin. In addition, the core pin and the casting pin are structured to advance by a predetermined stroke in the solidification process and perform casting by partially pressing the thick portion.
[0008]
In this way, by causing the core pin and the core pin arranged in a state of being opposed to the mold to advance, partial pressure is applied to the inside of the cast product, thereby suppressing the occurrence of a cast hole inside the cast product.
[0009]
Here, as a casting technique using a semi-solid metal in a solid-liquid coexisting state, for example, a thixocast method or a rheocast method is representative, and the former is a special metal billet (cooling and solidification of the semi-solid metal once (for example). Solid), a predetermined amount of metal billet is reheated to a solid-liquid coexistence temperature range to form a semi-solid metal slurry, and the latter is heated to a solid-liquid coexistence temperature range to cool and solidify. Although there is a difference such as molding without any change, any method may be used.
[0010]
Moreover, as a cast pin, you may make it provide separately for partial pressurization, and you may make it utilize the existing cast pin.
[0011]
According to a second aspect of the present invention, a cast pin for forming a crank journal portion fastening hole is used as the cast pin.
[0012]
Since such a crank journal part fastening hole is formed in the thick part of the cylinder block, it is possible to effectively pressurize the thick inside where the cast hole is likely to be generated and improve the internal quality.
Moreover, since such a cast pin is an existing facility, it can be dealt with with a slight improvement.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the accompanying drawings.
Here, FIG. 1 is an example of a manufacturing apparatus used in the method for manufacturing a cylinder block according to the present invention, FIG. 2 is an explanatory view showing the positional relationship between a core pin for forming a water jacket of a casting mold and a core pin, 3 is a plan view of the cylinder block, FIG. 4 is a cross-sectional view taken along line AA of FIG. 3, FIG. 5 is a bottom view of the cylinder block, and FIG.
[0014]
First, an example of a manufacturing apparatus used in the present invention will be described with reference to FIG. As shown in FIG. 1, the manufacturing apparatus 1 includes a molten metal holding furnace 2 that holds the molten aluminum alloy A, a pumping robot 4 that pumps the molten metal A for one shot and transfers it to the heat insulating crucible 3, and the molten metal A. A supply robot 5 that holds the crucible 3 when the crucible 3 is transferred, a plurality of stirrers 6 that receive the crucible 3 to be carried and cool the molten metal A while stirring, and a metal slurry A that has been semi-solidified A casting mold 7 for forming the cylinder block is provided.
[0015]
The supply robot 5 holds the empty crucible 3 and feeds it to the receiving unit 10 so that the molten metal A supplied from the pumping robot 4 can be received in the crucible 3 and the crucible 3. When the molten metal A is supplied, the crucible 3 is transferred to the cradle 6u of the stirrer 6, and when the molten metal A is cooled on the cradle 6u to become a metal slurry, the crucible 3 is held again and cast. It is transferred to the slurry inlet 7a of the metal mold 7 so that the internal metal slurry can be charged.
[0016]
The stirrer 6 is provided with a cooling metal 8 that is immersed in the molten metal A in the crucible 3 on the cradle 6u and stirred, and the molten metal A is cooled to a predetermined temperature while stirring the molten metal A. The metal slurry is in a solid-liquid coexistence state.
[0017]
As shown in FIG. 2, the casting mold 7 has a water jacket forming core pin 11 projecting into the cavity from the mold 7x on one side and the mold 7y on the other side so as to face each other in the cavity. A pair of projecting core pins 12 are provided. The core pin 11 can be moved forward and backward by a predetermined stroke by an upper hydraulic cylinder 13, and the core pin 11 can be moved forward and backward by a lower hydraulic cylinder 14.
[0018]
On the other hand, the cast cylinder block S includes a water jacket j that surrounds the cylinder bore b as shown in FIGS. 3 and 4 and opens to the deck surface d, and a deck as shown in FIG. A crank journal portion tightening hole c formed on a surface opposite to the surface d is provided, and the water jacket j is formed by the core pin 11, and the crank journal portion tightening hole c is The molded pin 12 is used for molding.
[0019]
Further, among the cast inside of the cylinder block S, the side wall and the like of the boundary portion of the adjacent cylinder bore b is a thick portion, particularly as in the cross-sectional portion taken along the line AA in FIG. As shown in FIG. 8, a casting hole e is likely to occur inside, and pressure leakage is likely to occur through a cylinder head coupling hole k formed in the periphery. Therefore, the core pin 11 and the core pin 12 are used for partial pressurization inside the cast product in the casting process as described below.
[0020]
Next, a method for casting a cylinder block according to the present invention will be described.
The molten aluminum alloy A in the molten metal holding furnace 2 shown in FIG. 1 is held at about 650 ° C., for example, and one shot of such molten metal A is pumped out by the pumping robot 4.
[0021]
At this time, the supply robot 5 receives the empty crucible 3 from the cradle 6u at a predetermined location and waits at the receiving unit 10, and when the melt A for one shot is poured into the crucible 3 from the robot 4, The supply robot 5 places the crucible 3 containing the molten metal A back on the original cradle 6u and places it.
Incidentally, in this cradle 6u, in order to prevent the molten metal A from being cooled at once, the molten metal A is maintained at a predetermined temperature by a heating mechanism.
[0022]
Next, the cooling metal 8 of the stirrer 6 descends while rotating and is immersed in the molten metal A in the crucible 3 to stir the molten metal A. Then, when the temperature of the molten metal A is cooled to a constant temperature to form a metal slurry in a solid-liquid coexistence state, the cooling metal 8 is pulled up, and the crucible 3 is gripped by the supply robot 5 to be cast mold 7 To the slurry inlet 7a.
[0023]
Then, when the crucible 3 is inverted and the metal slurry is charged from the slurry charging port 7a, the cavity of the casting mold 7 is pressurized and filled as shown in FIG. 6 (a).
The metal slurry begins to solidify in the cavity, but some casting holes e are generated inside the thick wall, etc. even in the casting using the metal slurry.
[0024]
Therefore, in the process of solidifying the metal slurry, as shown in FIG. 6B, the water jacket forming core pin 11 and the core pin 12 are advanced by a predetermined stroke by the hydraulic cylinders 13 and 14, respectively. Pressurize. In the embodiment, the water jacket forming core pin 11 is advanced by 10 mm, and the core pin 12 is advanced by 50 mm.
[0025]
For this reason, generation | occurrence | production of the casting hole e which existed inside is suppressed, the airtightness in the water jacket j is improved, and the cylinder block S with good internal quality is cast.
By the way, when a conventional die casting method (HPDC) using molten aluminum is used, the core pin 11 and the core pin 12 are moved forward by the same procedure and partially pressed to cast, thereby completely preventing defects due to the occurrence of the cast hole e. From this, it has been found that the effect is particularly remarkable when partial pressure is applied to casting using a metal slurry.
[0026]
At this time, the core pin 12 uses the existing equipment for forming the crank journal portion fastening hole c, and therefore can be easily configured with slight improvements.
[0027]
The present invention is not limited to the above embodiment. What has substantially the same configuration as the matters described in the claims of the present invention and exhibits the same operational effects belongs to the technical scope of the present invention.
For example, the metal slurry may be manufactured by reheating a dedicated billet, and the advance stroke amount of the core pin 11 and the core pin 12 is an example.
[0028]
【The invention's effect】
As described above, the cylinder block manufacturing method according to the present invention uses a core pin for forming a water jacket and a casting mold in which a cast pin is provided at a position facing the core pin, This is generated inside the cast product because the cavity of the metal mold is pressurized and filled with semi-solid aluminum alloy, and the core pin and core pin are moved forward by a predetermined stroke during the solidification process. It is possible to prevent problems caused by the cast hole.
At this time, as described in claim 2, it is preferable to use an existing cast pin for forming the crank journal portion fastening hole as the cast pin, because it can be easily configured.
[Brief description of the drawings]
FIG. 1 is an example of a manufacturing apparatus used in a cylinder block manufacturing method according to the present invention. FIG. 2 is an explanatory diagram showing the positional relationship between a core pin for forming a water jacket of a casting mold and a core pin. 3] Plan view of cylinder block [FIG. 4] AA cross-sectional view of FIG. 3 [FIG. 5] Bottom view of the Cinder block [FIG. 6] Action diagram for explaining partial pressurization [FIG. 7] Conventional die casting method Explanatory drawing showing the state of occurrence of a cast hole by (HPDC) [FIG. 8] Explanatory drawing of water jacket pressure leakage in the conventional method [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus, 7 ... Mold for casting, 11 ... Core pin, 12 ... Cast-out pin, S ... Cylinder block, j ... Water jacket, c ... Crank journal part fastening hole, e ... Cast hole.

Claims (4)

A manufacturing method for manufacturing a cylinder block in which a water jacket is opened on a deck surface with a casting mold, the casting mold facing a core pin for forming the water jacket and a position of the core pin and a core pin to, casting mold a semi-solidified aluminum alloy pressure filled into the cavity of, by a predetermined stroke advancing the core pin and core pin for the water jacket formed in the coagulation process, the counter A method of manufacturing a cylinder block, characterized in that the thick wall portion between the core pin for forming the water jacket and the casting pin is partially pressurized and cast.  2. The method of manufacturing a cylinder block according to claim 1, wherein the core pin is a core pin for forming a crank journal portion fastening hole. A casting mold for casting a cylinder block in which a water jacket is opened to a deck surface by pressurizing and filling a semi-solid aluminum alloy into a cavity, and the casting mold includes a core pin for forming a water jacket. The core pin and the core pin are opposed to the position of the core pin and become a thick portion between the core pin. A casting mold characterized by casting with partial pressurization. 4. The casting mold according to claim 3, wherein the casting pin is a casting pin for forming a crank journal portion fastening hole.

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