Casting device

A casting device includes a bore formation core and a water jacket formation core. When a cavity is formed, gas existing in a space between both cores is suctioned through a flow path formed in the bore formation core under operation of a suctioning device. When the bore formation core is viewed from a side, this flow path exists above a virtual axial line that passes a center of the bore formation core and extends along a longitudinal direction of the bore formation core.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-059358 filed on Mar. 30, 2020, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a casting device for obtaining a cylinder block.

Description of the Related Art

In one of the conventionally known internal-combustion engines for automobiles, a plurality of cylinder bores are formed in a cylinder block and the adjacent cylinder blocks form a V shape, which is a so-called V type. Usually, a water jacket that serves as a path for cooling water is formed around the cylinder bores. The cylinder block including such cylinder bores and water jacket can be obtained by casting with the use of a casting device as disclosed in Japanese Utility Model Registration No. 2510455, for example.

In this case, the casting device includes a fixed die that is positioned and fixed, a movable die that approaches or separates from the fixed die, a bore formation core that is used to form a cylinder bore, and a water jacket formation core that is used to form a water jacket. With the fixed die and the movable die, a cavity is formed. In addition, the bore formation core and the water jacket formation core are provided to a movable platen that supports the movable die.

As described in Japanese Laid-Open Patent Publication No. 08-132210, a water jacket formation core is provided to surround an outer peripheral side of a bore formation core. Here, at a movable platen, an actuator that integrally displaces the bore formation core and the water jacket formation core is supported. The actuator is disposed at a position farther from a cavity than the bore formation core and the water jacket formation core, and makes both cores advance toward or retract from the cavity. In other words, the bore formation core and the water jacket formation core approach or separate from the cavity integrally under the operation of the actuator.

In the casting, before the dies are closed, a release material is applied (for example, spray application) to the fixed die, the movable die, the bore formation core, and the water jacket formation core. It is assumed that the release material scattering in the air at this time enters the casting device through a space between the movable platen and the actuator, and moreover goes around to the bore formation core side. When the release material has entered the cavity from the bore formation core, the amount of release material in the cavity becomes excessive.

In order to avoid this, in the technique according to Japanese Utility Model Registration No. 2510455, a flow path for compressed air is formed in a bore formation core (“bore pin” in Japanese Utility Model Registration No. 2510455) and a release material is blown off using air blow with dies opened. Thus, the entry of the release material into a cavity through the bore formation core is prevented. Instead of using the air blow, an O-ring may be provided at a portion of the bore formation core that is not embedded in a molten metal filling the cavity. With the O-ring, the space between the bore formation core and a water jacket formation core can be sealed.

SUMMARY OF THE INVENTION

In the middle of filling the cavity with the molten metal, most part of the gas in the cavity is discharged into the air from a vent hole formed in the casting device. However, it is not easy for the gas in the space between the bore formation core and the water jacket formation core to go around to enter the vent hole. Therefore, the gas is entrapped near an opening of a cylinder bore on a gasket surface, for example. If the gas is entrapped too much, a casting defect such as a blow hole is easily formed and in this case, the quality of a cylinder block deteriorates.

A main object of the present invention is to provide a casting device that can obtain a cylinder block with high quality while preventing gas from being entrapped in a molten metal.

According to one embodiment of the present invention, a casting device includes a fixed die and a movable die that approaches or separates from the fixed die, and forms a cavity to obtain a cylinder block with the fixed die and the movable die, the casting device including: a bore formation core configured to form a cylinder bore in the cylinder block; a water jacket formation core surrounding the bore formation core from an outer peripheral side and configured to form a water jacket around the cylinder bore; an actuator configured to displace the bore formation core and the water jacket formation core integrally in a direction of getting close to or being separated from the cavity; a seal member disposed in a space between the bore formation core and the water jacket formation core, and configured to section the space into a close side part that is close to the cavity and a separation side part that is apart from the cavity; and a suctioning device configured to suction gas in the close side part through a flow path formed in the bore formation core, wherein the bore formation core includes a near part that faces the close side part and is always exposed from molten metal in the cavity, a far part that faces the separation side part, and a bore formation part that protrudes from the near part toward the cavity and is embedded in the molten metal in the cavity; and the flow path includes a first opening formed on an outer surface of the near part and a second opening formed on an outer surface of the far part and connected to the suctioning device, and the flow path exists above a virtual axial line that passes a center of the bore formation core and extends along a longitudinal direction of the bore formation core when the bore formation core is viewed from a side.

According to the present invention, when the cavity is filled with the molten metal, the gas existing in the space between the bore formation core and the water jacket formation core can be removed from the space by the flow path formed at a predetermined part of the bore formation core. Thus, it is possible to prevent the gas from being entrapped in the molten metal, and therefore a casting defect is hardly formed in the cylinder block, which is a cast product. That is to say, the quality of the cylinder block is improved.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of a casting device according to the present invention is hereinafter described in detail with reference to the attached drawings. Note that “front (forward)” in the following description indicates the side closer to a cavity22inFIG. 2. In addition, “rear” indicates a direction opposite to “front (forward)”, that is, the side away from the cavity22.

FIG. 1andFIG. 2are schematic longitudinal cross-sectional views of a main part when dies of a casting device10according to the present embodiment are opened and closed, respectively. This casting device10includes a fixed platen14where a fixed die12is provided, and a movable platen18where a movable die16is provided. The movable platen18can approach or separate from the fixed platen14under the operation of an open/close cylinder20. As the movable platen18approaches or separates from the fixed platen14, the movable die16approaches or separates from the fixed die12.

With the fixed die12and the movable die16that are in the closed state, the cavity22illustrated inFIG. 2is formed. In the present embodiment, the cavity22is to form a cylinder block of a six-cylinder V-type internal combustion engine. Note that at least one of the movable platen18and the fixed platen14includes a vent hole (not illustrated) used to exhaust gas in the cavity22into the air when the cavity22is filled with molten metal. To the fixed platen14, an ejector pin that is not illustrated is provided in a manner that the ejector pin can be exposed to the cavity22or can retract from the cavity22.

In the movable platen18, first sliding grooves24and second sliding grooves26each having a shape extending radially from the movable die16are formed. The first sliding groove24and the second sliding groove26are formed to have a shape like a letter of V in a recumbent state. Three first sliding grooves24and three second sliding grooves26are formed in parallel along a direction perpendicular to the paper surface ofFIG. 1andFIG. 2. Note that inFIG. 1andFIG. 2, one of the three first sliding grooves24and one of the three second sliding grooves26are illustrated.

In the first sliding groove24, a bore pin displacement cylinder30(actuator) is housed. A rod of the bore pin displacement cylinder30is connected to a core holder32that slides along the first sliding groove24. As illustrated inFIG. 3, a bore pin34is provided as a bore formation core at a front end of the core holder32that faces the cavity22. The bore pin34includes a bore formation part36, a near part38, and a far part40in this order from a front end side, which is close to the cavity22, to a rear end side. In this case, the diameters of the bore formation part36, the near part38, and the far part40are different from each other. Specifically, the diameter of the bore formation part36is small, the diameter of the far part40is large, and the diameter of the near part38is a little smaller than that of the far part40.

The bore formation part36protruding from the near part38to the cavity22is a part that is embedded in the molten metal when the cavity22is filled with the molten metal. When the bore formation part36is extracted from the molten metal whose fluidity has been lost to some extent, the cylinder bore is formed. On the other hand, the near part38and the far part40are always exposed from the molten metal in the cavity22. That is to say, the near part38and the far part40are not involved in the formation of the cylinder bore.

The inner diameter of a water jacket formation core42is large at a portion facing the bore formation part36and the near part38, and small at a portion facing the far part40. Each side peripheral wall (side wall) of the bore formation part36and the near part38is apart from an inner peripheral wall (inner wall) of the water jacket formation core42along the entire circumference. Therefore, a space44is formed between the bore formation part36and the near part38of the bore pin34, and the water jacket formation core42. The water jacket formation core may also be referred to as “WJ core” below.

As illustrated inFIG. 3andFIG. 5, a lower part of a side peripheral wall (lower part of side wall) of the far part40, where the diameter is the maximum, is in contact with a lower part of the inner peripheral wall (lower part of inner wall) of the WJ core42. By this contact, the bore pin34is supported by the WJ core42and thus, the bore pin34is positioned. On the other hand, an upper part of the side peripheral wall (upper part of side wall) of the far part40is apart from an upper part of the inner peripheral wall (upper part of inner wall) of the WJ core42as illustrated inFIG. 4. That is to say, a lower part of the space44is a little closed by a lower part of the far part40, and a side part and an upper part of the space44are narrowed by a side part and an upper part of the far part40.

On the side peripheral wall of the far part40, a first annular groove46and a second annular groove48are formed along a circumferential direction. To these first annular groove46and second annular groove48, a first O-ring50and a second O-ring52are fitted as sealing members. The first O-ring50and the second O-ring52seal between the side peripheral wall of the far part40of the bore pin34, and the inner peripheral wall of the WJ core42.

Inside the bore pin34, a plurality of (for example, two) flow paths56are formed. Each flow path56includes an inner hole58linearly extending toward the near part38from a rear end surface of the far part40of the bore pin34that faces the core holder32, and an inclined path60that is inclined toward an upper part of the side peripheral wall of the near part38(seeFIG. 3in particular). The inclined path60is inclined from the far part40(rear end) to the near part38(front end), and opens at the side peripheral wall of the near part38. In this manner, the flow path56includes a first opening62(particularly, seeFIG. 4) present at the side peripheral wall of the near part38, and a second opening64(seeFIG. 3) present at the rear end surface of the far part40. Note that the first opening62is formed at a portion that is near the first O-ring50and on the front side closer to the bore formation part36than the first O-ring50.

FIG. 3illustrates a virtual axial line X that splits the bore pin34into two in a height direction. When the bore pin34is viewed from the side, this virtual axial line X extends along a longitudinal direction of the bore pin34, passing the center of the bore pin34. The flow path56including the first opening62and the second opening64exists entirely above the virtual axial line X.

A rear end of the WJ core42is fitted to a fitting concave part70formed at a front end of the core holder32. By this fitting and a connection of the WJ core42to the core holder32through a bolt or the like as necessary, the WJ core42is supported by the core holder32. In this manner, both the bore pin34and the WJ core42are supported by the core holder32. Therefore, as the rod of the bore pin displacement cylinder30advances or retracts, the bore pin34and the WJ core42are displaced integrally with the core holder32.

The WJ core42has an approximately cylindrical shape, and surrounds the bore pin34from the outer peripheral side. The WJ core42is shorter than the bore pin34and a part of the bore formation part36of the bore pin34is exposed from the front end of the WJ core42. As described above, the space44is formed between the inner peripheral wall of the WJ core42and the side peripheral wall of the bore pin34. This space44is sectioned by the first O-ring50and the second O-ring52into a close side part72that is close to the cavity22and a separation side part74that is apart from the cavity22.

Since the first O-ring50and the second O-ring52are provided to the far part40of the bore pin34, the close side part72of the space44faces the near part38and the bore formation part36while the separation side part74faces the far part40. In addition, since the first opening62of the flow path56is formed in the near part38and the second opening64of the flow path56is formed in the far part40, the flow path56extends from the close side part72to the separation side part74.

Back toFIG. 1andFIG. 2, a structure similar to that in the first sliding groove24is also provided in the second sliding groove26. Therefore, the same component as that described above is denoted by the same reference sign and the detailed description thereof is omitted.

In the present embodiment, the bore pins34adjacent to each other (or facing each other) in an up-down direction are inclined to form a V shape in the recumbent state. That is to say, the lower bore pin34is inclined so that the front end is at a higher position than the rear end, and the upper bore pin34is inclined so that the rear end is at a higher position than the front end. Note that three upper bore pins34and three lower bore pins34are arranged in parallel along the direction perpendicular to the paper surface ofFIG. 1andFIG. 2.

Due to the influence from the gravity, the lower and upper bore pins34are all inclined so that the front end side is directed upward and the rear end side is directed downward with respect to the extending direction of the first annular groove46and the second annular groove48. Therefore, as described above, the lower part of the side peripheral wall of the far part40of the bore pin34is in contact with the lower part of the inner peripheral wall of the WJ core42. In addition, between the side peripheral wall of the near part38of the bore pin34and the inner peripheral wall of the WJ core42, the space44becomes small on the lower side and large on the upper side as illustrated inFIG. 4. That is to say, a separation distance D1on the lower side is smaller than a separation distance D2on the upper side.

The separation distance D2between the upper part of the side peripheral wall of the near part38and the upper part of the inner peripheral wall of the close side part72of the WJ core42is set to 50 μm or less. Note that since the bore pin34is positioned by bringing the lower part of the side peripheral wall of the far part40and the lower part of the inner peripheral wall of the WJ core42in contact with each other, the separation distance D2can be set to 50 μm or less with high accuracy. Thus, the upper part of the side peripheral wall of the near part38of the bore pin34and the upper part of the inner peripheral wall of the close side part72of the WJ core42can be separated from each other sufficiently.

Each flow path56of the bore pin34is connected to a front end of a flow pipe76through the second opening64. Rear ends of the flow pipes76are converged to a switch valve78. By this switch valve78, all the flow pipes76communicate with any of an exhaust pipe80or a supply pipe82selectively at the same time. Here, the exhaust pipe80is connected to a suction pump84as a suctioning device. In addition, the supply pipe82is connected to a compressor86(fluid supply device) that supplies compressed air as a blowing fluid. Therefore, under the operation of the suction pump84, the gas in the space44can be suctioned, and the compressed air can be supplied to the space44under the operation of the compressor86.

The casting device10according to the present embodiment is basically configured as described above, and the operation effect thereof is described from the viewpoint of the operation of the casting device10. The following operation is basically performed in accordance with sequence control operation of a control device that is not illustrated.

Before the casting work, a release material is applied to the fixed die12, the movable die16, the bore pin34, the WJ core42, and the like while the dies are open as illustrated inFIG. 1. This application is performed by, for example, applying the release material from an application gun provided at an end arm of a robot (not illustrated), that is, by spray application. The release material partially scatters in a mist form in the air, and then adheres to the casting device10.

Then, the dies are closed to perform the casting work. That is to say, the bore pin displacement cylinder30is energized and accordingly, the bore pin34and the WJ core42are displaced in a direction of approaching the movable die16integrally with the core holder32. The suction pump84may be energized at the time when the bore pin displacement cylinder30is energized. Here, the flow path56communicates with the exhaust pipe80through the flow pipe76and the switch valve78.

Next, the open/close cylinder20is energized so that movable platen18approaches the fixed platen14. As a result, the movable die16and the fixed die12are closed to form the cavity22as illustrated inFIG. 2. Here, a part of the release material that has adhered to the casting device10may enter the movable platen18along the core holder32and the bore pin34, and go to the cavity22. In this case, however, the second O-ring52stops the release material. Thus, the release material is prevented from going forward over the far part40of the bore pin34. As a result, it is possible to prevent the amount of release material in the cavity22from becoming excessive.

After the cavity22is formed, the molten metal is poured into the cavity22. While the molten metal is poured, most part of the gas in the cavity22is discharged into the air outside the cavity22through the vent hole.

In addition, the gas existing in the space44between the near part38and the bore formation part36of the bore pin34, and the WJ core42is suctioned into the inclined path60through the first opening62of the flow path56under the operation of the suction pump84. Here, as described above, the separation distance D2between the upper part of the side peripheral wall of the bore pin34and the upper part of the inner peripheral wall of the WJ core42is larger than the separation distance D1between the lower part of the side peripheral wall of the bore pin34and the lower part of the inner peripheral wall of the WJ core42. The flow path56is formed above the virtual axial line X of the bore pin34, and thus deviated to the upper side of the bore pin34. Therefore, near the first opening62, the upper part of the side peripheral wall of the near part38of the bore pin34and the upper part of the inner peripheral wall of the close side part72of the WJ core42, are sufficiently apart from each other. Accordingly, the gas existing in the space44is suctioned easily.

The gas flows in the flow pipe76and the exhaust pipe80through the inclined path60and the second opening64of the inner hole58, and is discharged into the atmospheric air through the suction pump84. In the present embodiment, the first opening62of the flow path56is formed near a first seal member. Therefore, the gas existing in the space44flows smoothly in a direction of separating from the cavity22and accordingly, the occurrence of vortex of the gas in the space44can be suppressed. As a result, the gas can be removed efficiently from the space44.

Furthermore, in the present embodiment, the separation distance D2between the upper part of the side peripheral wall of the near part38of the bore pin34and the upper part of the inner peripheral wall on the close side of the WJ core42is set to 50 μm or less. In addition, the separation distance D1between the lower part of the side peripheral wall of the near part38of the bore pin34and the lower part of the inner peripheral wall on the close side of the WJ core42is smaller than the separation distance D2. Thus, it becomes difficult for powder burr to enter the space44. That is to say, the space44or the first opening62is hardly blocked with the powder burr. Therefore, the gas existing in the space44can be suctioned continuously.

For these reasons, it is possible to prevent a large amount of gas from being entrapped in a part of the molten metal that becomes the gasket surface or a part to become the cylinder bore, for example. Accordingly, the occurrence of a casting defect such as a blow hole in the cylinder block can be suppressed and the cylinder block with excellent quality can be obtained.

After a predetermined time from the end of the pouring of the molten metal, for example, when the molten metal has solidified to such a degree that the fluidity is lost, the open/close cylinder20is energized. That is to say, the movable platen18and the movable die16are displaced to be separated from the fixed platen14and the fixed die12, and thus the dies are opened. As a result, the casting device10returns to the state illustrated inFIG. 1, and the cylinder block is exposed. The cylinder block adheres to the fixed die12.

At substantially the same time as when the open/close cylinder20is energized, the switch valve78is operated to block the communication (connection) between the flow pipe76and the exhaust pipe80, and the flow pipe76and the supply pipe82communicate (connect) with each other. Note that the compressor86is energized before this switching. For example, the compressor86may be energized when the dies start to be closed.

Therefore, the compressed air from the compressor86flows to the second opening64of the flow path56(inner hole58) through the supply pipe82and the flow pipe76. Moreover, the compressed air is discharged from the first opening62of the inclined path60toward the space44. That is to say, air blow is started. Even if the powder burr has entered the space44, this air blow makes the powder burr go out of the space44. At this time, the bore pin34is not yet released from the cylinder block; therefore, the compressed air is in contact with the cylinder block. Therefore, the cylinder block is cooled efficiently.

Next, as the bore pin displacement cylinder30is energized, the bore pin34and the WJ core42are displaced integrally with the core holder32in a direction of separating from the movable die16. In addition, the ejector pin provided to the fixed platen14is displaced so as to be exposed from the cavity22, and pushes the cylinder block out of the fixed die12. Thus, the cylinder block is released from the die. Therefore, the compressed air discharged from the first opening62is in contact with not just the bore pin34and the WJ core42but also the movable die16and the fixed die12. Accordingly, the movable die16and the fixed die12can be cooled efficiently.

In a case where the release material, a casting piece, or the like remains in the bore pin34, the WJ core42, the movable die16, and the fixed die12, such residue is blown by the compressed air. That is to say, by the compressed air, the casting device10is cleaned. Therefore, the additional cleaning is not necessary. As a result, the cycle time from the start of the application of the release material to the end of the cleaning can be shortened.

Here, the inclined path60is inclined from the far part40(rear end) to the near part38(front end). Therefore, the powder burr, the release material, the casting piece, or the like is pressed by the compressed air so as to go forward over the first opening62. Therefore, the first opening62will not be blocked with the powder burr, the release material, the casting piece, or the like. Accordingly, the air blow can be continued for a long time.

The present invention is not limited to the aforementioned embodiment in particular, and various changes are possible in the range not departing from the concept of the present invention.

For example, in the casting device10, the bore pins34that are adjacent to each other (face each other) may rise to form a V shape. Alternatively, in the casting device10, the cylinder bores may be arranged in a straight line and a so-called inline internal combustion engine may be obtained.

Further alternatively, in addition to the flow path56formed above the virtual axial line X, another flow path may be formed below the virtual axial line X.

Although not illustrated in particular, a cylinder sleeve may be externally fitted to the bore pin34.

Although the first O-ring50and the second O-ring52are used as the seal member in this embodiment, the number of seal members may be one, or three or more. In the case of the three or more seal members, the first opening62may be provided ahead of the foremost seal member. In this case, the space44is sectioned into the close side part72, which is ahead of the foremost seal member, and the separation side part74behind the rearmost seal member.