Casting device

An object is to provide a casting device that is capable of maintaining depressurization in a cavity. A casting device (1) is configured to move an extrusion pin (3), slidably inserted in an insertion hole (29) formed in a mold (2), into a cavity (20) in the mold to release a casted product. The casting device (1) includes a depressurized space creator (4) configured to create a depressurized space (40) on a reverse side of a cavity surface to define the cavity (20). The depressurized space creator (4) covers an opening of the insertion hole (29) to maintain depressurization in the cavity (20).

TECHNICAL FIELD

The present invention relates to a casting device.

BACKGROUND

In general, a casting device extrudes an extrusion pin (ejecting pin) penetrating a mold toward a cavity to release a casted product, when the casted product casted with mold is taken out. (see Patent Document 1, for example)

The extrusion pin described in the Patent Document 1 has a proximal end with a flange portion (43a) held between ejecting plates (41, 43) and has a distal end inserted through a loose-fit hole (23b) of a main mold (21) and a through hole (23) of a movable mold (20) to the cavity (C).

PRIOR ART REFERENCE

Patent Document

SUMMARY OF THE INVENTION

Problem to be Solved

In a vacuum casting mold described in Patent Document 1, when air is sucked to depressurize a cavity (C) to reduce gas or air from being entrained into a melt, the air in a recess portion (22b) enters the cavity (C) through gaps in the loose-fit hole (23b) and the through hole (23). Therefore, there has been a problem that an internal pressure in the cavity (C) is not easily decreased to maintain depressurization in the cavity (C).

In view of this, the present invention has been invented to solve the above problem and an object thereof is to provide a casting device that is capable of maintaining depressurization in a cavity.

Means to Solve Problem

To solve the above problem, a casting device according to the present invention is configured to move an extrusion pin, slidably inserted in an insertion hole formed in a mold, into a cavity in the mold to release a casted product, the casting device including a depressurized space creator configured to create a depressurized space on a reverse side of a cavity surface to define the cavity. The depressurized space creator covers an opening of the insertion hole. The “reverse side of a cavity surface” here, for example, in a mold including a fixed mold and a movable mold, refers to a side of the mold where the movable mold is arranged (rear side). In other words, the “reverse side of a cavity surface” refers to an opposite side (back side) of the movable mold to a surface of the cavity surface.

Advantageous Effects of the Invention

The present invention provides a casting device that is capable of maintaining depressurization in a cavity.

EMBODIMENTS OF THE INVENTION

A casting device1according to an embodiment of the present invention will be described with reference toFIGS.1and2. Note that the casting device1will be described with reference to an example in which a movable mold21arranged on a rear side (back side of a cavity surface2a) is moved in a front-rear direction (toward an obverse side or a reverse side). For convenience, the description will be made with an up-down direction and a right-left direction in the drawings as a front-rear direction and a right-left direction, respectively.

As shown inFIG.1, the casting device1has a melt teemed into a cavity20between the movable mold21and a fixed mold22of a mold2and cooled, to form a casted product. After the melt is filled in the cavity20formed in the mold2to cast the casted product, the casting device1releases the casted product by extruding an extrusion pin3, slidably inserted in an insertion hole29formed in the mold2, into the cavity20.

The casting device1mainly includes the mold2, a plurality of the extrusion pins3, a depressurized space creator4to create a depressurized space40on a rear side of the mold2, a die-casting machine6driving the extrusion pins3, a depressurizing device7to depressurize the depressurized space40, and a depressurizing device8to depressurize the cavity20. Note that the casting device1can be of a horizontal type in which the movable mold21is moved horizontally or can be of a vertical type in which the movable mold21is moved vertically. Hereinafter, the horizontal type casting device1will be described as one of examples.

The mold2is a casting mold mainly including the movable mold21which is movable, and the fixed mold22arranged to face the movable mold21. The mold2can be of a horizontally split type split into multiple surfaces and a shape and a structure thereof are not particularly limited. During casting, a melt of metal such as an aluminum alloy, a magnesium alloy or a zinc alloy is fed into the cavity20in the mold2from a holding furnace (not shown) arranged in front of the mold2or the like. The depressurized space creator4to create the depressurized space40is arranged on the back side of the cavity surface2aof the mold2, particularly on a rear side (back side) of the insertion hole29in which the extrusion pin3is inserted.

The movable mold21includes a mold capable of being moved forward and backward relative to the fixed mold22by a forward-and-backward motion mechanism (not shown) provided in a die-casting machine6. The movable mold21includes a movable mold insert23arranged on a side, closer to the cavity20, of a movable main mold25, the movable main mold25arranged to cover the movable mold insert23from behind, and a die base27fixed on the rear surface of the movable main mold25. The movable mold21includes a core to form a rear half part of the casting product and the cavity surface2a. The movable mold21and the movable mold insert23are formed with the insertion hole29in which the extrusion pin3is inserted so as to be freely movable in a front-rear direction.

The fixed mold22includes a front mold fixed on a die plate (not shown). The fixed mold22includes a fixed mold insert24arranged to face a front side of the movable mold insert23, a fixed main mold26arranged to face a front side of the movable main mold25, and a casting bush28arranged to orient frontward from an outer surface of the fixed mold insert24. The fixed mold22has a fixed-mold cavity to form a front half of the casted product. The movable mold21has positioning keys (not shown) for aligning positions arranged on the front surface of the movable mold21. The fixed mold22has recess portions (not shown) arranged on the rear surface of the fixed mold22to face the positioning keys. The recess portions respectively engage with the positioning keys to automatically align positions of the movable mold21and fixed mold22.

The extrusion pin3, as shown inFIG.2, is a releasing pin in a substantially cylindrical shape (rod shape) having a flange portion3bat a rear end thereof and an expanded diameter portion3a, having an expanded diameter, substantially in the center thereof. The extrusion pin3is configured to seal the depressurized space40by the expanded diameter portion3awhile being moved rearward (backward). That is, the extrusion pin3closes a sealing hole43awith the expanded diameter portion3apressing against a sealing member43while being moved backward. The extrusion pin3is moved in the front-rear direction by an extrusion mechanism61. Note that many of the extrusion pins3are not shown inFIGS.1and2, and, however, the casting device1is provided with 20 to 30 pins, for example.

The expanded diameter portion3aincludes a cylindrical sliding part3cformed in a central portion and a tapered surface3dformed in front of, and behind, the sliding part3c. The tapered surface3dof the extrusion pin3pushes against the sealing member43to close an extrusion pin insertion hole4a, thereby maintaining sealing of the depressurized space40. The flange portion3bis a thick plate-shaped portion formed at the rear end of the extrusion pin3.

The depressurized space creator4is a member arranged on the rear side (reverse side) of the movable main mold25having the insertion hole29to define a sealed chamber, including the depressurized space40with air depressurized, behind the movable main mold25. The depressurized space creator4includes a depressurized space creating member41, a sealing member holding plate42, the sealing member43, a sealing member O1, and a fastening bolt (not shown).

As shown inFIG.2, the depressurized space creating member41is formed with the extrusion pin insertion hole4ain which the extrusion pin3is inserted, a suction hole4bto which a suction hose71is connected, a recess portion4cforming the depressurized space40, and a pole part4d. The depressurized space creating member41is fixed on the rear surface of the movable main mold25with the fastening bolt (not shown) via the sealing member O1.

The extrusion pin insertion hole4ais a hole in which the expanded diameter portion3aof the extrusion pin3is inserted so as to be moved freely in the front-rear direction. The extrusion pin insertion hole4ais formed from the depressurized space creating member41to the sealing member holding plate42, extending through the sealing member holding plate42, on the rear side, from the front surface of the depressurized space creating member41in the recess portion4c.

The suction hole4bis a through hole to which the suction hose71joined to the depressurizing device7is attached. The suction hole4bis formed to extend through a wall for the recess portion4c. The recess portion4cis formed of a groove which defines a space in a reversed concave shape and is recessed from the front surface of the depressurized space creating member41. The recess portion4ccovers the openings of the plurality of insertion holes29. The recess portion4cis wholly continuous such that air can be sucked through the single suction hole4b. The pole part (not shown) is a pole-shaped part formed in the recess portion4c.

The sealing member holding plate42is a thick plate member fixed with the fastening bolt (not shown) via the sealing member43on the rear side of the depressurized space creating member41. The sealing member holding plate42includes the extrusion pin insertion hole4aand a sealing member mounting hole42aformed at a front open end of the extrusion pin insertion hole4ain the sealing member holding plate42.

The sealing member43is engaged in the sealing member mounting hole42aof the sealing member holding plate42and is made of a rubber to seal the extrusion pin insertion hole4a. The sealing member43is formed of a tubular member having the sealing hole43ain which the extrusion pin3is inserted.

The sealing member O1is a member arranged between the depressurized space creating member41and the movable mold21to seal the depressurized space40, and is formed of an annular packing such as an O ring. The sealing member O1is arranged on a front surface of the depressurized space creating member41, near an outer periphery of the pressurized space creating member41. A sealing member O2is a member arranged between the movable mold insert23and the movable main mold25to seal the circumference of the insertion hole29, and is formed of an annular packing such as an 0 ring.

As shown inFIG.1, the die-casting machine6mainly includes a forward-and-backward motion device (not shown) that moves the movable mold21forward and backward, and the extrusion mechanism61that moves the extrusion pin3forward and backward.

The forward-and-backward motion device (not shown) is a device positioning the movable mold21on the rear surface (back surface) of the fixed mold22to close the mold and moving the movable mold21rearward away from the fixed mold22.

The extrusion mechanism61is a device to extrude and release a casted product in the mold2. The extrusion mechanism61includes a front extrusion plate62, a rear extrusion plate63, a fastening bolt B1, and an extrusion mechanism coupling rod64.

The front extrusion plate62is a flat plate member to engage and hold the flange portion3bof the extrusion pin3. The rear extrusion plate63is a flat plate member to hold the flange portion3bof the extrusion pin3between the front extrusion plate62and the rear extrusion plate63. A plurality of the fastening bolts B1are fixtures to fix the rear extrusion plate63to the front extrusion plate62. The extrusion mechanism coupling rod64is a coupling rod having a front end thereof connected to the rear surface of the rear extrusion plate63and having a rear end thereof connected to a driving part (not shown) of the extrusion mechanism61. The driving part (not shown) includes, for example, a hydraulic cylinder device having a piston (not shown)

The depressurizing devices7,8are devices to depressurize the depressurized space40or the cavity20. The depressurizing device7includes, for example, an air pump to suck air in the depressurized space40. The depressurizing device8includes, for example, an air pump to suck air in the cavity20. The depressurizing devices7,8are attached so as to communicate with the depressurized space40or the cavity20with suction hoses71,81.

The holding furnace (not shown) is a furnace to reserve a melt, such as aluminum to be teemed into the mold2, in a heated condition.

Next, the operation of the casting device1according to the embodiment of the present invention will be described in order of casting steps, with reference toFIGS.1and2.

First, as shown inFIG.1, the movable mold21equipped with the movable mold insert23is placed and set on the rear side of the fixed mold22equipped with the movable mold insert24, and the mold is closed. Thereby, the mold2defines the cavity20therein.

Next, the mold2is pre-heated, and then the depressurizing device8sucks air in the cavity20for depressurization, to render the cavity20under a negative pressure. Further, the depressurizing device7is driven to render the depressurized space40under a negative pressure. Meanwhile, the expanded diameter portion3aof the extrusion pin3closes the extrusion pin insertion hole4a. This prevents the air in the depressurized space40from entering the cavity20via a gap between the insertion hole29and the extrusion pin3, resolving a problem that a pressure in the cavity20is not easily decreased.

Subsequently, a melt in the holding furnace (not shown) is teemed into the mold2to fill the cavity20with the melt. Meanwhile, the cavity20has a negative pressure, and thus the melt is easily teemed into the cavity20. After the melt is teemed into the mold2, the mold2is heated with heat of the melt conducted thereto.

Next, a temperature of the melt and mold2is made to reach a prescribed temperature, and then the movable mold21is moved backward with the forward-and-backward motion mechanism (not shown) to separate the movable mold21from the fixed mold22. Consequently, the extrusion pin3is moved forward with the extrusion mechanism61to release a casted product from the fixed mold22. This completes casting of the casted product with the casting device1.

As described above, the present invention, as shown inFIGS.1and2, provides the casting device1configured to move the extrusion pin3, slidably inserted in the insertion hole29formed in the mold2, into the cavity20in the mold2to release the casted product. The casting device1has the depressurized space creator4configured to create the depressurized space40on the reverse side of the cavity surface2a. The depressurized space creator4covers the opening of the insertion hole29.

As described above, the casting device1according to the present invention has the depressurized space creator4to create the depressurized space40on the reverse side (rear side) of the cavity surface2aof the mold2. Further, the depressurized space creator4covers the opening of the insertion hole29, thereby achieving depressurization of a portion, on the back side, of the insertion hole29, in which the extrusion pin3is inserted. Thus, the depressurized space creator4prevents the air in the depressurized space40from entering the cavity20via the insertion hole29, thereby maintaining depressurization in a cavity. As a result, this reduces gas or air from being entrained into the melt in the cavity20.

Further, as shown inFIG.2, the depressurized space creator4has the extrusion pin insertion hole4a, through which the extrusion pin3extending from the insertion hole29is inserted, and is arranged with the sealing member43having the sealing hole43athrough which the extrusion pin3is inserted. The extrusion pin3has the expanded diameter portion3ahaving an expanded diameter, and when moved backward in the rear direction, the diameter expansion part3amakes the depressurized space40sealed.

Consequently, when the extrusion pin3is moved backward, the expanded diameter portion3amakes the depressurized space40sealed, thereby preventing ambient air from entering the depressurized space40via the extrusion pin insertion hole4ain which the extrusion pin3is inserted. Also, a negative pressure in the depressurized space40is maintained, thereby preventing the air in the depressurized space40from entering the cavity20via the insertion hole29. This decreases a pressure difference between the pressure in the depressurized space40and that in the cavity20.

Further, as shown inFIG.2, the sealing member43is formed of the tubular member having the sealing hole43a. When the extrusion pin3is moved backward, the expanded diameter portion3apresses the sealing member43to close the sealing hole43a.

The sealing member43is formed of the tubular member having the sealing hole43a, thereby reducing the sealing member43in size. When the extrusion pin3is moved backward, the expanded diameter portion3acloses the sealing hole43a, to maintain sealing of the depressurized space40.

Further, as shown inFIG.2, the depressurized space creator4is formed with the suction hole4bthrough which the air in the depressurized space40is sucked to depressurize the depressurized space40. The depressurized space creator4is formed with the suction hole4bfor depressurizing the depressurized space40, thereby rendering the depressurized space40under a negative pressure by sucking the air in the depressurized space40through the suction hole4b.

The present invention is not limited to the above-described embodiment, and various modifications and changes are possible within the scope of the technical ideas, so that it should be appreciated that the present invention also covers those modified and changed inventions. Note that the same numerals are used for the configurations already described and descriptions thereof are omitted.FIG.3is a partially enlarged schematic vertical cross-sectional view of a first modification of the casting device according to the embodiment of the present invention.

In the embodiment described above, as shown inFIG.2, the depressurized space creator4having the tubular sealing member43has been described as an example, and, meanwhile, a shape of the sealing member is not limited to this shape. As shown inFIG.3, a sealing member43A can be formed of a single sheet member having a sealing hole43Aa. When the extrusion pin3is moved backward, the expanded diameter portion3acan press the sealing member43A to seal the sealing hole43Aa.

In this case, on a back side of the cavity surface2aof the mold2, the extrusion pins3are inserted and a depressurized space creator4A to define a depressurized space40A on a back side of the insertion hole29is provided. The depressurized space creator4A has an extrusion pin insertion hole4Aa, in which the extrusion pin3is inserted, and is arranged with the sealing member43A in a plate shape having the sealing hole43Aa, which communicates with the extrusion pin insertion hole4Aa and in which the extrusion pin3is inserted.

When the extrusion pin3is moved backward, the expanded diameter portion3apresses the sealing member43A to close the sealing hole43Aa and makes the depressurized space40A sealed. A depressurized space creating member41A has a space in a reversed concave shape, when viewed in vertical cross-section. The depressurized space creating member41A has a sealing member holding plate42A framed in the space in a reversed concave shape, on a ceiling surface for the space, via the sealing member43A. The depressurized space creating member41A is fixed to a sealing member holding plate42A with a fastening bolt B3via the sealing member43A. The sealing member holding plate42A is fixed to the movable main mold25with a fastening bolt B2via sealing members O1, O3. Note that the fastening bolts B2, B3are provided at multiple places. The sealing member O3is provided between the movable main mold25and the sealing member holding plate42A around a place where the fastening bolt B2is provided. The sealing member O3is formed of an annular packing such as an O ring. Further, the depressurized space creator4A is formed with a suction hole4Ab, to which the suction hose71of the depressurizing device7(shown inFIG.1) is connected to suck the air in the depressurized space40A to depressurize the depressurized space40A.

Consequently, even when the sealing member43A is a sheet-shaped member having the sealing hole43Aa, the sealing member43A maintains sealing of the extrusion pin insertion hole4Aa, in which the extrusion pin3is inserted, to render the depressurized space40A under a negative pressure.

FIGS.4A,4B,4Care each a partially enlarged schematic vertical cross-sectional view of a second modification of the casting device according to the embodiment of the present invention, showing another shape of an expanded diameter portion of the extrusion pin.

The expanded diameter portion3aof the extrusion pin3can have any shape which abuts against the sealing member43to seal the extrusion pin insertion hole4a, and is not limited to one having the shape shown inFIG.2.

For example, as shown inFIG.4A, the expanded diameter portion3acan be an expanded diameter portion3a1made of an annular protrusion in a semicircular shape, a curved shape, or an arc shape in cross section, as viewed from an outer periphery of the extrusion pin3. Further, as shown inFIG.4B, the expanded diameter portion3acan be an expanded diameter portion3a2made of an annular protrusion protruding radially outward to have a flange shape in cross section, as viewed from the outer periphery of the extrusion pin3. Further, as shown inFIG.4C, the expanded diameter portion3acan be an expanded diameter portion3a3with an outer diameter expanded in a taper shape to have a thick diameter in cross section, as viewed from the outer peripheral of the extrusion pin3.

In the embodiment described above, as shown inFIG.2, the sealing member43having a cylindrical shape has been described as an example. Meanwhile, the shape of the sealing member43is not limited thereto. The sealing member43can be anything to seal the extrusion pin insertion hole4a, and can be an O ring having a circular shape in cross section, or a packing having an oval shape or a polygonal shape, such as a quadrangle shape, in cross section.

Further, in the first modification described above, the sealing member43A formed of the single sheet member has been described as an example, however, the number of sheets can be appropriately changed to two or more depending on an arrangement condition and the like.

LIST OF REFERENCE SIGNS