EP1254731A1

EP1254731A1 - Die casting method, die-cast article, and die casting machine

Info

Publication number: EP1254731A1
Application number: EP99947908A
Authority: EP
Inventors: Rokurou Shimada
Original assignee: Esumorudo YK; Daimaru Kogyo Ltd
Current assignee: SHIMADA, TAKESHI; Daimaru Kogyo Ltd
Priority date: 1999-10-14
Filing date: 1999-10-14
Publication date: 2002-11-06
Also published as: CN1379702A; WO2001026849A1

Abstract

An insert die 18 with a number of slits 18A is provided inside a cavity 16 located between a fixed die plate 12 and a movable die plate 14 of a die casting machine 10, and a breathable metal mold 20 is arranged at a location contacting the front end of the slit 18A. Molten metal can be injected up to the front end of the narrow slits 18A by applying negative pressure on the breathable metal mold 20 and degassing, when pouring in the molten metal.

Description

TECHNICAL FIELD

This invention relates to die casting methods, die cast articles, and die casting machines.

BACKGROUND ART

In the case of an IC of a compact electronic circuit of high-density, a great amount of heat is generated during its operation, and a heat dissipating plate (heat sink) is mounted onto the IC in close adherence to dissipate the heat generated in the IC to the atmosphere.
In this case, heat radiation efficiency of the above-mentioned heat sink becomes higher, as the contacting area between the heat sink and the atmosphere becomes extensive. Hence, in conventional methods, the heat sink was constructed so that it had a number of heat dissipation fins of sheet form provided with prescribed intervals on one face of a base plate using metals with high thermal conductivity such as aluminum.
In this case, the heat dissipation fins are made to be as thin as possible, and as much as possible, to improve the heat radiation efficiency by making the contacting area of the heat sink and the atmosphere more extensive.
There are also heat sinks provided with a number of heat dissipation pins of thin diameter, and of cylinder or prism form, which are used instead of the heat dissipation fins, to dissipate the heat of an IC of even smaller size, which conducts high-speed processing.
These heat sinks with heat dissipation fins or heat dissipation pins were manufactured mainly by die cast molding, aluminum extrusion (press molding), or processing by cutting in conventional methods, but the die cast molding was used most often from the standpoint of manufacturing cost.
However, there was a problem in die cast molding, such as the ones mentioned above, in that the molten metal did not reach the front end portions of slits or holes during the molding, when the slits or holes for forming the heat dissipation fins or heat dissipation pins were formed to have a small size.
Therefore, in conventional methods, the minimum limit of the thickness of a heat dissipation fin was considered to be a little less than 2mm at the front end, and the minimum limit of the diameter of a heat dissipation pin was considered to be a little over 2mm at the front end.

DISCLOSURE OF THE INVENTION

The present invention was devised in view of the above-mentioned conventional problem, and an object of the present invention is to provide a die casting method and a die casting machine that make it easy to form a heat dissipation fin of a thin wall, or a heat dissipation pin of thin diameter, and also to provide die cast articles that are cast by this die casting method.
A first invention of a die casting method, as described in claim 1, attains the above-mentioned object with a die casting method, comprising the steps of: arranging an insert die provided with a slit inside a cavity formed on an abutting face between a fixed die plate and a movable die plate, with a front end portion of the slit opening to said movable die plate side, the slit is for forming a plurality of thin wall portions parallel to a direction in which a work-piece is pushed out; arranging a breathable metal mold inside said movable die plate in contact with the front end portion of the slit of said insert die; and pouring molten metal into said cavity, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
A second invention of a die casting method, as described in claim 2, attains the above-mentioned object with a die casting method, comprising the steps of: arranging an insert die provided with a hole inside a cavity formed on an abutting face between a fixed die plate and a movable die plate, with a front end portion of said hole opening to said movable die plate side, the hole is for forming a plurality of pins parallel to a direction in which a work-piece is pushed out; arranging a breathable metal mold is arranged inside said movable die plate in contact with the front end portion of said hole of said insert die; and pouring molten metal into said cavity, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
A third invention of a die casting method, as described in claim 3, attains the above-mentioned object with a die casting method, comprising the steps of: arranging an insert die provided with a concave portion and a convex portion within this concave portion inside a cavity formed on an abutting face between a fixed die plate and a movable die plate, with a front end portion of said concave portion opening to said movable die plate side, the concave portion is for forming a thin wall portion intersecting at right angles with a direction in which a work-piece is pushed out and the convex portion is for forming a hole for the thin wall portion arranging a breathable metal mold inside said movable die plate, opposing said convex portion; and pouring molten metal into said cavity, while negative pressure is applied to said breathable metal mold to suck air from a surface at said fixed die plate side.
A fourth invention of a die casting method, as described in claim 4, attains the above-mentioned object with a die casting method, comprising the steps of: forming a concave portion at a location adjacent to a cavity formed on an abutting face between a fixed die plate and a movable die plate, and on at least one of the abutting surfaces of said fixed die plate and said movable die plate; filling a breathable metal of sheet form into said concave portion; and pouring molten metal into said cavity, while negative pressure is applied to said breathable metal of sheet form to suck air from said abutting face.
A first invention of a die cast article, as described in claim 5, attains the above-mentioned object with a cast heat sink article, wherein an insert die for heat sink provided with a slit for forming a plurality of heat dissipation fins parallel to a direction in which a work-piece is pushed out is arranged inside a cavity formed on an abutting face between a fixed die plate and a movable die plate of a die casting machine, with a front end portion of the slit opening to said movable die plate side;
a breathable metal mold is arranged inside said movable die plate in contact with the front end portion of the slit of said insert die for heat sink; and said cast heat sink article is formed by pouring molten metal into said cavity and solidifying, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
In the aforementioned cast heat sink article, the aforementioned heat dissipation fin can be made to have a thickness of 0.3 to 1.5mm at the front end.
A second invention of a die cast article, as described in claim 7, attains the above-mentioned object, with a cast heat sink article, wherein an insert die for heat sink provided with a hole for forming a plurality of heat dissipation pins parallel to a direction in which a work-piece is pushed out is arranged inside a cavity formed on an abutting face between a fixed die plate and a movable die plate of a die casting machine, with a front end portion of said hole opening to said movable die plate side; a breathable metal mold is arranged inside said movable die plate in contact with the front end portion of the hole of said insert die for heat sink; and said cast heat sink article is formed by pouring molten metal into said cavity and solidifying, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
In the aforementioned cast heat sink article, the aforementioned heat dissipation pin can be made to have a diameter of 1.0 to 2.0mm at the front end.
A third invention of a die cast article, as described in claim 9, attains the above-mentioned object with a sheet metal cast article with apertures; wherein an insert die, provided with a concave portion for forming a thin wall portion intersecting at right angles with a direction in which a work-piece is pushed out and a convex portion inside the concave portion, for forming an aperture on the thin wall portion, is arranged inside a cavity formed on an abutting face between a fixed die plate and a movable die plate of a die casting machine, with said concave portion opening to said movable die plate side; a breathable metal mold is arranged inside said movable die plate, opposing said convex portion; and said sheet metal cast article with apertures are formed by pouring molten metal into said cavity and solidifying, while negative pressure is applied to said breathable metal mold to suck air from a surface on said fixed die plate side.
A first invention of a die casting machine, as described in claim 10, attains the above-mentioned object with a die casting machine, comprising: a fixed die plate and a movable die plate with a cavity formed on an abutting face between these die plates; an insert die arranged inside this cavity, and provided with slits for forming a plurality of thin wall portions parallel to a direction in which a work-piece is extruded, the insert die being arranged with a front end of the slit opening to the aforementioned movable die plate side; a breathable metal mold arranged inside the aforementioned movable die plate, in contact with the front end of the aforementioned slit; and negative pressure forming means for applying negative pressure to the aforementioned breathable metal mold to suck air from a contacting surface with the front end of the aforementioned slit, when pouring molten metal into the aforementioned cavity.
In the aforementioned die casting machine, the aforementioned work-piece is a heat sink, and the slit of the aforementioned insert die is for forming a heat dissipation fin of the heat sink, and a thickness of the slit can be made to be 0.3 to 1.5mm.
In the aforementioned die casting machine, the aforementioned breathable metal mold can have a concave portion formed at a backside of a portion opposing the slit of the aforementioned insert die to make it thinner than other portions.
A second invention of a die casting machine, as described in claim 13, attains the above-mentioned object with a die casting machine, comprising: a fixed die plate and a movable die plate with a cavity formed on an abutting face between these die plates; an insert die arranged inside this cavity, and provided with holes for forming a plurality of pins parallel to a direction in which a work-piece is extruded, and also arranged with a front end of the hole opening to the aforementioned movable die plate side; a breathable metal mold arranged inside the aforementioned movable die plate, in contact with the front end of the aforementioned hole; and negative pressure forming means for applying negative pressure to the aforementioned breathable metal mold to suck air from a contacting surface with the front end of the aforementioned slit, when pouring molten metal into the aforementioned cavity.
In the aforementioned die casting machine, the aforementioned work-piece is a heat sink, the hole of the aforementioned insert die is for forming a heat dissipation pin of the heat sink, and a diameter of this hole can be made to be 1.0 to 2.0mm at the front end.
In the aforementioned die casting machine, the aforementioned breathable metal mold can have a concave portion formed at a backside of a portion opposing the aforementioned hole of the aforementioned insert die to make it thinner than other portions.
A third invention of a die casting machine, as described in claim 16, attains the above-mentioned object with a die casting machine comprising: a fixed die plate and a movable die plate with a cavity formed on an abutting face between these die plates; an insert die arranged inside this cavity, and provided with a concave portion for forming a thin wall portion intersecting at right angles with the direction in which a work-piece is extruded and a convex portion inside the concave portion, for forming apertures on the thin wall portion; a breathable metal mold arranged inside the aforementioned movable die plate, opposing the aforementioned convex portion; and negative pressure forming means for applying negative pressure to the aforementioned breathable metal mold to suck air from a surface on the aforementioned convex portion side, when pouring molten metal into the aforementioned cavity.
In the aforementioned die casting machine, the aforementioned breathable metal mold can have a concave portion formed at a backside of a portion opposing the convex portion of the aforementioned insert die, to make it thinner than other portions.
A fourth invention of a die casting machine, as described in claim 18, attains the above-mentioned object with a die casting, comprising: a fixed die plate and a movable die plate with a cavity formed on an abutting face between these die plates, and with a concave portion formed adjacent to this cavity on at least one of the abutting surfaces of the aforementioned fixed die plate and movable die plate; a breathable metal of sheet form filled into this concave portion; and negative pressure forming means for applying negative pressure to the aforementioned breathable metal of sheet form to suck air from the aforementioned abutting surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a principal part of a die casting machine according to an embodiment of this invention;
FIG. 2 is a perspective view showing a heat sink with heat dissipation fins, manufactured by the same die casting machine;
FIG. 3 is a perspective view showing an insert die portion of the same die casting machine;
FIG. 4 is a sectional view showing the principal part of the same die casting machine;
FIG. 5 is a perspective view showing a heat sink with heat dissipation pins, cast by the same die casting machine;
FIG. 6 is a perspective view showing an insert die for the same heat sink with heat dissipation pins;
FIG. 7 is a perspective view showing a sheet metal member with apertures, cast by a die casting machine; and
FIG. 8 is a sectional view showing a principal part of a die casting machine for casting the same sheet metal member with apertures.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described in detail hereinafter, with references to the drawings.
As shown in FIG. 1, a die casting machine 10 (general view not shown) according to the embodiment of the present invention has: a fixed die plate 12 and a movable die plate 14 with a cavity 16 formed on an abutting face between these plates; an insert die 18 that is arranged inside this cavity 16 and is provided with slits 18A for forming a plurality of thin wall portions parallel to the direction in which a work-piece is extruded; a breathable metal mold 20 arranged inside the aforementioned movable die plate 14, in contact with front ends of the aforementioned slits 18A; and negative pressure forming means 22 which applies negative pressure to the aforementioned breathable metal mold 20, so that air is sucked from a contacting face with the front ends of the aforementioned slits 18A, when pouring molten metal into the aforementioned cavity 16.
Reference symbol 24A in FIG. 1 denotes a guide pin mounted on the fixed die plate 12 side, and reference symbol 24B denotes a guide pin hole provided on the aforementioned movable die plate 14 side, and into which the aforementioned guide pin 24A is inserted through, in a slidable manner in the axial direction.
Referring to FIG. 1, a runner 26, which communicatively connects with the aforementioned cavity 16, is provided on the aforementioned movable die plate 14, and molten metal is supplied to this runner 26 from a pouring inlet 28 formed on the fixed die plate 12 side.
Reference symbol 30 in FIG. 1 denotes a basin, and reference symbol 32 denotes a degassing hole.
The aforementioned insert die 18 is for forming a heat sink 34 that has a plurality of cooling fins 34A formed in unity on top of a base plate 34B, as shown in FIG. 2, and a concave portion for base plate 18B is formed continuously, at the end portion of the aforementioned number of slits 18A, on the opposite side of the aforementioned movable die plate 14. The width (gap) at the front end of the aforementioned slit 18A is made to be 0.3 to 1.5mm, and the width at the base side is made wider than the front end, to constitute a draft angle.
The aforementioned breathable metal mold 20 is usually used as a metal mold that serves also as a degasser in injection-molding plastic, and it is constituted by metal that has minute communicative connection holes formed throughout its body, such as one formed with spherical powders of stainless steel sintered by hot isostatic pressing, which is known as Hiporas (trade name; manufactured by Kobe Steel, Ltd), or one formed with high alloy gold powder and high alloy short fiber mixed and sintered, for example.
In this die casting machine 10, the aforementioned breathable metal mold 20 is made to have a size that corresponds with the whole extent of the aforementioned insert die 18, and its central portion is arranged to correspond with the aforementioned slits 18A.
The aforementioned breathable metal mold 20 is of a planar form, and front ends of vacuum pipes 22A and 22B, which constitute a portion of the aforementioned negative pressure forming means 22, are screwed in and fixed to the upper and lower ends of the mold as shown in FIG. 4. Negative pressure supplied from a negative pressure source 22C such as a vacuum pump is transmitted to the breathable metal mold 20 through the vacuum pipes 22A and 22B, and air is sucked from an end surface of the breathable metal mold 20 on the aforementioned insert die 18 side.
In FIG. 4, reference symbol 36 denotes an ejector plate, reference symbol 38A denotes a spacer block, and reference symbol 38B and 39 denotes insulating materials.
A number of the aforementioned cavities 16 are formed when the size of heat sink 34 is compact, to constitute a so-called multi cavity mold. But in this embodiment, a single cavity mold will be described.
When die casting a heat sink 34, shown in FIG. 2, with the aforementioned die casting machine 10, the movable die plate 14 is clamped to the aforementioned fixed die plate 12, and molten metal such as melted aluminum is poured in from the pouring inlet 28 in this state, then necessary pressing-in is conducted, and the molten metal is cooled and solidified inside the cavity 16.
In this process, gas is generated from the molten metal, and this gas is discharged from the aforementioned degassing hole 32. This gas also passes through the slit 18A of the insert die 18 by the negative pressure applied from the aforementioned vacuum pipes 22A and 22B to the breathable metal mold 20, onto which the front end of the slit 18A is brought into contact. Furthermore, this gas is sucked out of the breathable metal mold 20 by the vacuum pipes 22A and 22B. Therefore, the molten metal goes around to the front ends of the slits 18A, even when their width is narrow.
Then, after the molten metal is cooled and solidified, the movable die plate 14 is opened, and the formed heat sink 34 is pushed out by the ejector plate 36 to be brought out as a product.
The aforementioned breathable metal mold 20 is made for plastic molding as mentioned before, and there is a possibility in which the mold is melted or damaged by coming into contact with the pressed-in molten metal. However, since the width of the slit 18A is narrow, and the breathable metal mold 20 comes in contact with the molten metal only at the front end portion of the slit 18A, the temperature of the pressed-in molten metal is lowered a great deal when it reaches the location where it contacts the breathable metal mold 20, and the molten metal does not melt or damage the breathable metal mold 20.
In this embodiment, the thickness of the aforementioned slit 18A is made to be 0.3 to 1.5mm. Therefore, the thickness of the cooling fin 34A of the cast heat sink 34 also becomes 0.3 to 1.5mm.
It is not possible to mold such a cooling fin 34A of sheet form, unless degassing is done effectively from between the slits 18A using the breathable metal mold, as mentioned above.
When die casting a heat sink 40, which is provided with heat dissipation pins 42 such as the ones shown in FIG. 5, with the aforementioned die casting machine 10, an insert die 44 such as the one shown in FIG. 6 is used.
This insert die 44 is provided with holes 44A that are for forming a plurality of pins parallel to the pushing out direction of the work-piece, and a concave portion for base plate 44B that exists in continuity on the base side of the hole 44A. The front end of the hole 44A is arranged to contact the breathable metal mold 20, which is similar to the one mentioned above, provided on the movable die plate 14 side. The diameter of the aforementioned hole 44A at the front end is made to be 1.0 to 2.0mm.
By constituting in this way, it is possible to form a heat sink 40 provided with heat dissipation pins 42 of narrow diameter, as shown in FIG. 5, which were not possible to manufacture in conventional methods, by pouring molten metal into the cavity 16 and applying pressure, while applying negative pressure to the breathable metal mold 20 through the vacuum pipes 22A and 22B, which is similar to the case mentioned above.
A die casting machine 50 for casting a sheet member 48 provided with a plurality of apertures 46, as shown in FIG. 7, will be described next.
As shown in FIG. 8, this die casting machine 50 is provided with: a fixed die plate 52 and a movable die plate 54 with a cavity 56 formed on an abutting face between these plates; an insert die 58 arranged inside this cavity 56, and provided with a concave portion 58A for forming a thin wall portion intersecting at right angles with the direction a work-piece is ejected and a convex portion 58B inside this concave portion 58A, for forming apertures on the thin wall portion; a breathable metal mold 60 that is arranged inside the aforementioned movable die plate 54, opposing the aforementioned convex portion 58B; and negative pressure forming means 22, similar to the one mentioned above, which applies negative pressure to the aforementioned breathable metal mold 60 to suck air from a surface on the aforementioned convex portion 58B side, when pouring molten metal into the aforementioned cavity 56.
With this die casting machine 50, the gas generated in the casting process is sucked and discharged from the front end of the convex portion 58B, which is the portion that will become the aperture 46 of the sheet member 48, by the breathable metal mold 60. Hence, molten metal flows easily into the concave portion 58A, which is the portion where the sheet metal is formed, and into which it is difficult to make the molten metal go around, and it is possible to surely die cast mold a sheet member 48. The breathable metal mold 60 does not get melted or damaged, because the molten metal does not flow into the convex portion 58.
A defect will generate in the sheet member 48, when the aforementioned breathable metal mold 60 is installed at a location opposing the concave portion 58A of the aforementioned insert die 58, because gas gathers around this place.
In general, a so-called burr is formed, when molten metal is poured into cavities 16 or 56, such as the ones mentioned above, and pressurized, and not enough degassing is done, because gas gets into the abutting surface between the aforementioned fixed die plates 12 or 52, and the aforementioned movable die plates 14 or 54, and expands this surface, and the molten metal flows into this surface.
In such a case, breathable metal plates 62, made of the same material as the breathable metal mold 20, are arranged outside and adjacent to the cavity 16, and on either one of the aforementioned fixed die plate 12 or movable die plate 14, as shown in a two-dotted chain-line in FIG. 4. By doing this, the gas, which tries to flow in between the fixed die plate 12 and the movable die plate 14 and tries to expand the gap between these plates, is discharged promptly by the negative pressure applied to the breathable metal plate 62 to prevent a generation of burrs.
The aforementioned breathable metal plates 62 are made, so that negative pressure can be applied to them from the vacuum pipes 22A and 22B, as in the aforementioned breathable metal mold 20.

INDUSTRIAL APPLICABILITY

With this invention, it is possible to die cast portions of sheet metal form, and pin portions of small diameter, which were impossible to cast in conventional methods due to insufficient degassing.

Claims

A die casting method, comprising the steps of:

arranging an insert die provided with a slit inside a cavity formed on an abutting face between a fixed die plate and a movable die plate, with a front end portion of the slit opening to said movable die plate side, the slit is for forming a plurality of thin wall portions parallel to a direction in which a work-piece is pushed out;

arranging a breathable metal mold inside said movable die plate in contact with the front end portion of the slit of said insert die; and

pouring molten metal into said cavity, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
A die casting method, comprising the steps of:

arranging an insert die provided with a hole inside a cavity formed on an abutting face between a fixed die plate and a movable die plate, with a front end portion of said hole opening to said movable die plate side, the hole is for forming a plurality of pins parallel to a direction in which a work-piece is pushed out;

arranging a breathable metal mold is arranged inside said movable die plate in contact with the front end portion of said hole of said insert die; and

pouring molten metal into said cavity, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
A die casting method, comprising the steps of:

arranging an insert die provided with a concave portion and a convex portion within this concave portion inside a cavity formed on an abutting face between a fixed die plate and a movable die plate, with a front end portion of said concave portion opening to said movable die plate side, the concave portion is for forming a thin wall portion intersecting at right angles with a direction in which a work-piece is pushed out and the convex portion is for forming a hole for the thin wall portion;

arranging a breathable metal mold inside said movable die plate, opposing said convex portion; and

pouring molten metal into said cavity, while negative pressure is applied to said breathable metal mold to suck air from a surface at said fixed die plate side.
A die casting method, comprising steps of:

forming a concave portion at a location adjacent to a cavity formed on an abutting face between a fixed die plate and a movable die plate, and on at least one of the abutting surfaces of said fixed die plate and said movable die plate;

filling a breathable metal of sheet form into said concave portion; and

pouring molten metal into said cavity, while negative pressure is applied to said breathable metal of sheet form to suck air from said abutting face.
A cast heat sink article, wherein
an insert die for heat sink provided with a slit for forming a plurality of heat dissipation fins parallel to a direction in which a work-piece is pushed out is arranged inside a cavity formed on an abutting face between a fixed die plate and a movable die plate of a die casting machine, with a front end portion of the slit opening to said movable die plate side;
a breathable metal mold is arranged inside said movable die plate in contact with the front end portion of the slit of said insert die for heat sink; and
said cast heat sink article is formed by pouring molten metal into said cavity and solidifying, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
The cast heat sink article according to claim 5, wherein said heat dissipation fin is made to have a thickness of 0.3 to 1.5mm at the front end.
A cast heat sink article, wherein
an insert die for heat sink provided with a hole for forming a plurality of heat dissipation pins parallel to a direction in which a work-piece is pushed out is arranged inside a cavity formed on an abutting face between a fixed die plate and a movable die plate of a die casting machine, with a front end portion of said hole opening to said movable die plate side;
a breathable metal mold is arranged inside said movable die plate in contact with the front end portion of the hole of said insert die for heat sink; and
said cast heat sink article is formed by pouring molten metal into said cavity and solidifying, while negative pressure is applied to said breathable metal mold to suck air from a contacting face with an opening at an end portion of the insert die.
The cast heat sink article according to claim 7, wherein said heat dissipation pin is made to have a diameter of 1.0 to 2.0mm at the front end.
A sheet metal cast article with apertures, wherein
an insert die, provided with a concave portion for forming a thin wall portion intersecting at right angles with a direction in which a work-piece is pushed out and a convex portion inside the concave portion, for forming an aperture on the thin wall portion, is arranged inside a cavity formed on an abutting face between a fixed die plate and a movable die plate of a die casting machine, with said concave portion opening to said movable die plate side;
a breathable metal mold is arranged inside said movable die plate, opposing said convex portion; and
said sheet metal cast article with apertures are formed by pouring molten metal into said cavity and solidifying, while negative pressure is applied to said breathable metal mold to suck air from a surface on said fixed die plate side.
A die casting machine, comprising:

a fixed die plate and a movable die plate with a cavity formed on an abutting face between said die plates;

an insert die arranged inside said cavity, and provided with a slit for forming a plurality of thin wall portions parallel to a direction in which a work-piece is pushed out, the insert die being arranged with a front end of the slit opening to said movable die plate side;

a breathable metal mold arranged inside said movable die plate in contact with the front end of said slit; and

negative pressure forming means for applying negative pressure to said breathable metal mold to suck air from a contacting surface with the front end of said slit, when pouring molten metal into said cavity.
The die casting machine according to claim 10, wherein said work-piece is a heat sink; and
the slit of said insert die is for forming a heat dissipation fin of the heat sink, and a thickness of the slit is made to be 0.3 to 1.5mm.
The die casting machine according to claim 10 or claim 11, wherein said breathable metal mold has a concave portion formed at a backside of a portion opposing the slit of said insert die to make it thinner than other portions.
A die casting machine, comprising:

a fixed die plate and a movable die plate with a cavity formed on an abutting face between said die plates;

an insert die arranged inside said cavity, and provided with a hole for forming a plurality of pins parallel to a direction in which a work-piece is pushed out, the insert die being arranged with a front end of said hole opening to said movable die plate side;

a breathable metal mold arranged inside said movable die plate in contact with the front end of said hole; and

negative pressure forming means for applying negative pressure to said breathable metal mold to suck air from a contacting face with the front end of said hole, when pouring molten metal into said cavity.
The die casting machine according to claim 13, wherein
said work-piece is a heat sink; and
the hole of said insert die is for forming a heat dissipation pin of the heat sink, and a diameter of the hole is made to be 1.0 to 2.0mm, at the front end.
The die casting machine according to claim 12 and claim 13, wherein said breathable metal mold has a concave portion formed at a backside of a portion opposing said hole of said insert die to make it thinner than other portions.
A die casting machine, comprising:

a fixed die plate and a movable die plate with a cavity formed on an abutting face between the die plates;

an insert die arranged inside said cavity, and provided with said concave portion for forming a thin wall portion intersecting at right angles with a direction in which a work-piece is pushed out and a convex portion inside the concave portion, for forming an aperture on the thin wall portion;

a breathable metal mold arranged inside said movable die plate, opposing said convex portion; and

negative pressure forming means for applying negative pressure to said breathable metal mold to suck air from a surface on said convex portion side, when pouring molten metal into said cavity.
The die casting machine according to claim 16, wherein said breathable metal mold has a concave portion formed at a backside of a portion opposing the convex portion of said insert die to make it thinner than other portions.
A die casting machine, comprising:

a fixed die plate and a movable die plate with a cavity formed on an abutting face between said die plates;

a concave portion formed adjacent to the cavity on at least one of the abutting surfaces of said fixed die plate and said movable die plate;

a breathable metal of sheet form filled into said concave portion; and

negative pressure forming means for applying negative pressure to said breathable metal of sheet form to suck air from said abutting surface.