JPH11309555A - Casting method with die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the frequency of a maintenance to a gap for gas exhausting by hardly clogging this gap. SOLUTION: In a casting method with die casting, with which the gas in a die is exhausted from the gap for gas exhausting, formed in a product forming surface in the die at the time of injecting molten metal, at the time of opening the die 10, the gas is blown from the gap to a cavity side. In this way, etc., invaded into the gap during exhausting the gas is removed and also, the dust from the outer part and releasing agent, etc., are not invaded into the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting method for evacuating gas from a mold through a gas elimination gap formed on a product molding surface of the mold during injection of molten metal.

[0002]

2. Description of the Related Art A related die casting method is disclosed in Japanese Utility Model Laid-Open No. 63-6153. In the die casting method, when a negative pressure is applied to a gap formed on a mating surface of a fixed mold and a movable mold and a gas release gap formed on a product molding surface of the movable mold, a molten metal is injected. The gas in the mold is efficiently discharged from these gaps.

[0003]

Generally, the gap formed on the mating surface of the mold can be cleaned each time the mold is opened, so that burrs may be generated and the gap is set to a relatively large size. . However, it is difficult to clean the gap formed on the product molding surface, so that the gap is set to a narrow size that allows only gas to pass without the intrusion of molten metal. Therefore, when a negative pressure is applied to the gap, dust and the like are sucked together with the gas in the cavity, and the gap is likely to be clogged with time. In addition, in the die casting method, a mold release agent is sprayed on the product molding surface every cycle to improve mold release and molten metal flow of the product, so that the mold release agent enters the gap due to a capillary phenomenon and is clogged. There is.

[0004] Therefore, claims 1 and 2 of the present invention.
The object of the invention described in (1) is to make it difficult for dust or a release agent or the like to be clogged in a degassing gap formed on a product molding surface, and to reduce the maintenance frequency of the gap.

[0005]

The above-mentioned object is achieved by a die casting method having the following steps.
That is, in the die casting method according to the first aspect, the die is opened in the die casting method in which the gas in the mold is evacuated from the gas elimination gap formed on the product molding surface of the mold when the molten metal is injected. Sometimes, gas is released from the gap to the cavity side.

According to the present invention, when the mold is opened, gas is released from the gap to the cavity side, so that dust and the like entering the gap when the molten metal is injected can be discharged, and dust and a release agent from the outside can be discharged. Will not enter the gap. For this reason, the gap is hardly clogged, and the maintenance frequency of the gap can be reduced.

According to a second aspect of the present invention, in the die casting method of the first aspect, a gas is released from the gap toward the cavity when the release agent is sprayed on the product molding surface. .

According to the present invention, the gas can be released when the release agent, which is the largest cause of clogging, is blown out, so that clogging can be efficiently prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A die casting method according to an embodiment of the present invention will be described below with reference to FIGS. The die casting method according to the present embodiment relates to a method for casting an open deck type cylinder block. FIGS. 1 and 2 are longitudinal sectional views of a die casting mold 10 used for carrying out the casting method. It is shown.
The die casting mold 10 forms a fixed mold 12 for molding a crankcase portion of the cylinder block, a slide mold 14 for molding an outer wall of the cylinder block, an upper surface of the cylinder block, a cylinder bore, a water jacket, and the like. And a movable mold 16 that performs the above-described operations.

The slide die 14 has a structure that opens and closes integrally with the movable die 16 and is clamped to the movable die 16 from the lateral direction (the horizontal direction in the drawing). The movable mold 16 and the slide mold 14 that have been clamped are lowered and fitted to the fixed mold 12. In this state, the clamping of the die casting mold 10 is completed (see FIG. 2), and a cavity 18 for product molding is formed therein. The mold opening is performed in the reverse procedure of the mold clamping. Fig. 1 shows the die casting mold 1 during mold opening
Represents 0.

The movable die 16 has a mating surface 16m whose lower surface is in surface contact with the slide die 14, and a molding surface 16f for a product (upper surface of a cylinder block) is formed at the center of the mating surface 16m. The molding surface 16
A groove-shaped overflow portion 16c is formed at a predetermined position on the mating surface 16m surrounding f. A water jacket insert 28 forming a water jacket is positioned at the center of the molding surface 16f, and a bore insert 26 for forming a cylinder bore is mounted inside the water jacket insert 28 by the number of cylinders. I have. Since the bore inserts 26 are positioned side by side in the horizontal direction, only one bore insert 26 is shown in FIGS. 1 and 2.

The bore insert 26 is an insert in which a product forming portion 26f on the distal end side (lower end side) has a substantially cylindrical shape, and a central shaft portion 26c above the product forming portion 26f is a water jacket insert 28. It is fitted into the through hole 28h. Further, the bore insert 26 is provided with a flange-like pressing plate 26b on the central shaft portion 26c, so that the insertion amount of the bore insert 26 into the through hole 28h can be kept constant. ing.

FIG. 3 is a detailed sectional view taken along the line III-III of FIG. 1 and shows a fitting portion 27 between the bore insert 26 and the through-hole 28h of the water jacket insert 28 as viewed from the cavity 18 side. I have. The clearance of the fitting portion 27 is set to a value that allows gas to pass but does not allow molten metal to enter.
The fitting portion 27 is hereinafter referred to as a first gas vent gap 27.

As shown in FIG. 4, a ring-shaped groove 28m is formed in the lower part of the through-hole portion 28h of the water jacket insert 28 at a position above the cavity 18 by a predetermined dimension in the circumferential direction. Have been. FIG.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3. On the other hand, a small hole 26k is formed in the bore insert 26 (see FIG. 4), and the lower end of the small hole 26k opens at the position of the groove 28m. Also, the upper end of the small hole 26k is a bore insert 2
6 is open at the end face of the holding plate 26b.

As shown in FIG. 3, guide holes 29k for a plurality of push pins are formed in the bore insert 26 and the water jacket insert 28. As shown in FIG. 5, the guide hole 29k guides the push-out pin 29p (see a two-dot chain line) between the product forming portion 26f of the bore insert 26 and the product forming portion 28f of the water jacket insert 28. From the holding plate 26b of the bore insert 26 to the groove 28m of the water jacket insert 28.
And penetrates straight up and down to the cavity 18. The clearance between the pushing pin 29p and the guide hole 29k is set to a value that allows gas to pass but does not allow molten metal to enter. The push pin 29p
The gap between the hole and the guide hole 29k is hereinafter referred to as a second gas venting gap 29.

As shown in FIG. 1, a space S is provided inside the movable die 16 above the bore insert 26 and the water jacket insert 28, and a bore insert is provided in the space S. A pressure pipe 16z connecting the 26 small holes 26k to the air pressure adjusting device 30 is provided. That is, the cavity 18 of the die casting die 10, in particular, the cavity 18 a between the product molded portion 26 f of the bore insert 26 and the product molded portion 28 f of the water jacket insert 28 is formed with the first gas release gap 27. The second gas venting gap 29 and the groove 28m, the small hole 26k, and the pressure pipe 16z communicate with the air pressure adjusting device 30.

The air pressure adjusting device 30 is a device for switching the groove 28m of the water jacket insert 28 between a positive pressure state and a negative pressure state at a predetermined timing, and includes a pump 32 for pressurizing air and a pressure for adjusting air pressure. Control valve 34
And a switching valve 36 for switching the flow direction of the air. The groove 28 of the water jacket insert 28
In order to set m to a positive pressure, the switching valve 36 is switched to the state shown in FIG. 1 by the controller C, the discharge side p2 of the pump 32 is connected to the pressure pipe 16z, and the suction side p1 of the pump 32 is opened to the atmosphere. As a result, pressurized air adjusted to a predetermined pressure by the pressure control valve 34 is supplied to the groove 28m, and the inside of the groove 28m is maintained at a positive pressure. As a result, the pressurized air is released from the first gas release gap 27 and the second gas release gap 29 to the cavity 18 side.

In order to reduce the pressure in the groove 28m of the water jacket insert 28 to a negative pressure, the switching valve 36 is switched to the state shown in FIG. 2 by the controller C so that the suction side p1 of the pump 32 communicates with the pressure pipe 16z. Then, the discharge side p2 of the pump 32 is opened to the atmosphere. As a result, the groove 28m is exhausted, and the inside of the groove 28m is maintained at a negative pressure. As a result, the gas in the cavity 18 flows from the first gas release gap 27 and the second gas release gap 29 to the groove 28m,
It is released to the outside via the small holes 26k, the grooves 28m and the like. Note that the air pressure adjusting device 30 is provided with a filter 38 on the suction side p1 of the pump 32 and on a portion that is open to the atmosphere.

Next, the die casting method according to the present embodiment will be described with reference to the casting timing chart of FIG. When the die casting mold 10 is open (see FIG. 1),
The groove 28m of the water jacket insert 28 is maintained at a positive pressure by an air pressure adjusting device 30, and a first gas release passage 27 and a second gas release passage formed in the bore insert 26 and the water jacket insert 28. From 29, air is released to the cavity 18 side.

Next, when the die casting mold 10 is clamped (see FIG. 2), the switching valve 36 of the air pressure adjusting device 30 is switched to the state of FIG. 2, and the suction side p1 of the pump 32 is connected to the pressure pipe 16z. The discharge side p2 is opened to the atmosphere.
As a result, the groove 28m is maintained at a negative pressure by the pump 32, and the gas in the cavity 18 is separated from the first gas release gap 27 and the second gas release gap 29 by the groove 28m.
m, the small hole 26k, the pressure pipe 16z, and the like. In this state, a plunger tip (not shown) operates, and molten metal is injected into the cavity 18 from the sleeve via the runner 18r and the gate 18e.

At this time, the gas in the cavity 18 is filled with a gap between the movable mold 16 and the slide mold 14, a gap between the slide mold 14 and the fixed mold 12, and a first gas vent gap. 27 and gap 29 for second degassing
Etc. are discharged out of the mold. In particular, the gas between the product forming portion 26f of the bore insert 26 and the product forming portion 28f of the water jacket insert 28, which is difficult to degas, is supplied to the first degassing gap 27 and the second degassing. Is efficiently discharged to the outside from the gap 29 for use through the groove 28m, the small hole 26k and the like (see FIGS. 4 and 5). The excess amount of the molten metal filled in the cavity 18 is removed from the gap between the mating surfaces of the movable mold 16 and the slide mold 14 by an overflow portion 16c.
To reach. As a result, shape defects on the upper surface of the cylinder block can be prevented. In this way, when the molten metal solidifies in the die casting mold 10, the mold is opened and the cylinder block, which is a product, is taken out.

When the product is taken out of the die casting mold 10, the switching valve 36 of the air pressure adjusting device 30 is switched to the state shown in FIG. 1, and the discharge side p2 of the pump 32 is connected to the pressure pipe 1
6z, and the suction side p1 is opened to the atmosphere. As a result, air is supplied to the groove 28m of the water jacket insert 28 and is maintained at a positive pressure, and the pressurized air in the groove 28m is filled with the first gas release gap 27 and the second gas release gap. It is discharged to the cavity 18 side through 29. As a result, when the molten metal is injected, the clearances 27, 2
The garbage and burrs that have entered inside 9 are discharged,
External dust and the like do not enter the gap.

Next, the die casting mold 10 (movable mold 16,
A release agent is sprayed on the product forming surfaces of the slide die 14 and the fixed die 12). At this time, in the movable mold 16, as described above, since air is released from the degassing gaps 27 and 29 of the bore insert 26 and the water jacket insert 28 to the cavity 18 side, the release agent and moisture Does not enter the gaps 27 and 29 due to capillary action.

As described above, when the sprayed release agent is dried, the mold is clamped, and the next casting is performed in the above-described procedure. As described above, according to the die casting method according to the present embodiment, air is continuously discharged from the gas release gaps 27 and 29 to the cavity side from the time of taking out the product to the time of closing the mold. Gap 27,2
9 is less likely to be clogged with dirt or a release agent, and the frequency of maintenance of the bore insert 26 and the water jacket insert 28 can be reduced.

Here, the gas vent clearances 27, 29
Since the release agent is most easily clogged, air may be released only when the release agent is sprayed. By doing so, the pressurized air can be used for another purpose except when the release agent is applied, and the utilization rate of the pressurized air is improved. Further, in the air pressure adjusting device 30 according to the present embodiment, the pump 32 and the switching valve 36 are used as the positive / negative pressure source. However, the present invention is not particularly limited thereto, and the positive pressure is directly obtained from the constant pressure air source. Alternatively, a negative pressure may be obtained by flowing compressed air from the constant pressure air source to the venturi.

Although the embodiments of the present invention have been described above, it is to be noted that the embodiments of the present invention have the following technical matters in addition to the technical matters described in the claims. Keep it. (1) The die casting method according to claim 1, wherein gas is discharged from a gap between an extrusion pin and a guide hole of the extrusion pin. (2) The die casting method according to claim 1, wherein gas is discharged from a gap between a bore insert and a water jacket insert when casting the open deck type cylinder block.

[0027]

According to the present invention, when the mold is open, gas is released from the gap to the cavity side, so that when the molten metal is injected, dust or the like that has entered the gap is discharged, and the molten metal is discharged from the outside. Dust and release agents do not enter the gap. For this reason, the gap is hardly clogged, and the maintenance frequency of the gap can be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a die-casting die used in carrying out a die-casting method according to an embodiment of the present invention in an open state.

FIG. 2 is a longitudinal sectional view of a die-casting mold used for carrying out a die-casting method according to an embodiment of the present invention in a mold-clamped state.

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a sectional view taken along the line VV of FIG. 3;

FIG. 6 is a drawing showing steps of a die casting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Fixed type 14 Slide type 16 Movable type 26 Bore insertion 26k Small hole 27 First gap for degassing 28 Water jacket insertion 28m Groove 29 Second gap for degassing 30 Air pressure adjusting device

Claims (2)

[Claims] 1. A die casting method for bleeding gas in a mold from a degassing gap formed on a product molding surface of a mold at the time of injection of molten metal, wherein a gas flows from the gap to a cavity side when the mold is open. Die casting method. 2. The die casting method according to claim 1, wherein a gas is released from the gap toward the cavity when a release agent is sprayed on the product molding surface.